Systems and methods for monitoring, managing, and preventing fatigue during ventilation

ABSTRACT

This disclosure describes systems and methods for determining patient fatigue during ventilation of a patient. The disclosure describes novel notification and/or management of patient fatigue during ventilation. Further, the disclosure describes system and methods for preventing diaphragm fatigue or weakness.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/671,815 (now U.S. Pat. No. 9,375,542), entitled“SYSTEMS AND METHODS FOR MONITORING, MANAGING, AND/OR PREVENTING FATIGUEDURING VENTILATION,” filed on Nov. 8, 2012, the entire disclosure ofwhich is hereby incorporated herein by reference.

INTRODUCTION

Medical ventilator systems have long been used to provide ventilatoryand supplemental oxygen support to patients. These ventilators typicallycomprise a source of pressurized oxygen which is fluidly connected tothe patient through a conduit or tubing. As each patient may require adifferent ventilation strategy, modern ventilators can be customized forthe particular needs of an individual patient. For example, severaldifferent ventilator modes have been created to provide betterventilation for patients in various different scenarios.

Monitoring, Managing, and Preventing Fatigue During Ventilation

This disclosure describes systems and methods for determining patientfatigue during ventilation of a patient. The disclosure describes novelnotification and/or management of patient fatigue during ventilation.Further, the disclosure describes system and methods for preventingdiaphragm fatigue or weakness.

In part, this disclosure describes a method for ventilating a patientwith a ventilator. The method includes:

a) monitoring a plurality of fatigue indicators;

b) establishing a baseline for the fatigue indicators;

c) determining a change from the baseline based on the monitored fatigueindicators;

d) comparing the change to a corresponding fatigue threshold;

e) detecting respiratory fatigue based on the step of comparing thechange to the fatigue threshold; and

f) displaying a fatigue notification after the step of detectingrespiratory fatigue.

Yet another aspect of this disclosure describes a ventilator system thatincludes: a pressure generating system, a ventilation tubing system, aplurality of sensors, a baseline module, a fatigue module, anotification module, and a graphical user interface. The pressuregenerating system is adapted to generate a flow of breathing gas. Theventilation tubing system includes a patient interface for connectingthe pressure generating system to a patient. The plurality of sensors isoperatively coupled to at least one of the pressure generating system,the patient, and the ventilation tubing system. The plurality of sensorsmonitors a plurality of parameters to generate sensor output. Thebaseline module determines a baseline for a plurality of fatigueindicators. The baseline module further determines a change in thefatigue indicators from the baseline based on the sensor output. Thefatigue module compares the change to corresponding fatigue thresholds.The fatigue module further determines that the patient is fatigued basedon the comparisons. Based on this comparison, the fatigue moduledetermines that the patient is fatigued. The notification moduledetermines an appropriate notification. The graphical user interfacedisplays the appropriate notification received from the notificationmodule. The appropriate notification message notifies a clinician thatthe fatigue module determined that the patient is fatigued

The disclosure further describes a computer-readable medium havingcomputer-executable instructions for performing a method for ventilatinga patient with a ventilator. The method includes:

a) repeatedly monitoring a plurality of fatigue indicators;

b) repeatedly establishing a baseline for the fatigue indicators;

c) repeatedly determining a change from the baseline based on themonitored fatigue indicators;

d) repeatedly comparing the change to a fatigue threshold;

e) detecting respiratory fatigue based on the step of comparing thechange to the fatigue threshold; and

f) displaying a fatigue notification after the step of detectingrespiratory fatigue.

These and various other features as well as advantages whichcharacterize the systems and methods described herein will be apparentfrom a reading of the following detailed description and a review of theassociated drawings. Additional features are set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the technology. Thebenefits and features of the technology will be realized and attained bythe structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawing figures, which form a part of this application,are illustrative of embodiments of systems and methods described belowand are not meant to limit the scope of the invention in any manner,which scope shall be based on the claims appended hereto.

FIG. 1 illustrates an embodiment of a ventilator.

FIG. 2 illustrates an embodiment of a method for determining patientfatigue while ventilating a patient on a ventilator.

FIG. 3A illustrates an embodiment of a method for notifying a clinicianof patient fatigue during ventilation.

FIG. 3B illustrates an embodiment of a method for managing patientfatigue during ventilation.

FIG. 3C illustrates an embodiment of a method for managing patientfatigue during ventilation.

FIG. 4 illustrates an embodiment of a method for determining if animplemented recommendation mitigated patient fatigue.

FIG. 5 illustrates an embodiment of a method for ventilating a patienton a ventilator.

DETAILED DESCRIPTION

Although the techniques introduced above and discussed in detail belowmay be implemented for a variety of medical devices, the presentdisclosure will discuss the implementation of these techniques in thecontext of a medical ventilator for use in providing ventilation supportto a human patient. A person of skill in the art will understand thatthe technology described in the context of a medical ventilator forhuman patients could be adapted for use with other systems such asventilators for non-human patients and general gas transport systems.

Medical ventilators are used to provide a breathing gas to a patient whomay otherwise be unable to breathe sufficiently. In modern medicalfacilities, pressurized air and oxygen sources are often available fromwall outlets. Accordingly, ventilators may provide pressure regulatingvalves (or regulators) connected to centralized sources of pressurizedair and pressurized oxygen. The regulating valves function to regulateflow so that respiratory gas having a desired concentration of oxygen issupplied to the patient at desired pressures and rates. Ventilatorscapable of operating independently of external sources of pressurizedair are also available.

While operating a ventilator, it is desirable to control the percentageof oxygen in the gas supplied by the ventilator to the patient. Further,as each patient may require a different ventilation strategy, modernventilators can be customized for the particular needs of an individualpatient. For example, several different ventilator breath types havebeen created to provide better ventilation for patients in variousdifferent scenarios.

For example, with the objective providing mechanical ventilator that ismore synchronous with a patient, some breath types incorporate positivefeedback algorithms. With positive feedback algorithms, the amount ofsupport provided by the ventilator is proportional to the monitoredpatient's work of breathing. Examples of breath types that utilizedpositive feedback algorithms are proportional assist (PA), tubecompensation (TC), and a diaphragmatic electromyography adjusted (DEA)breath type. These breath types provide support in proportion tomonitored work of breathing.

In mechanical ventilation, a proportional assist (PA) breath type refersto a type of ventilation in which the ventilator acts as an inspiratoryamplifier that provides pressure support based on the patient's work ofbreathing. The degree of amplification (the “support setting”) is set byan operator, for example as a percentage based on the patient's work ofbreathing (WOB). As used herein, the term “work of breathing” isintended to include any method for determining the amount effort thepatient utilizes to breathe, including work of breathing (Joules/Liter),power of breathing (Joules/minute), oxygen cost of breathing (VO₂),pressure time product, and tension time index. In one implementation ofa PA breath type, the ventilator may continuously monitor the patient'sinstantaneous inspiratory flow and instantaneous net lung volume, whichare indicators of the patient's inspiratory WOB. These signals, togetherwith ongoing estimates of the patient's lung compliance and lungresistance, allow the ventilator to compute a WOB and derive therefrom atarget pressure to provide the support that assists the patient'sinspiratory muscles to the degree selected by the operator as thesupport setting.

Various methods are known for calculating work of breathing and anysuitable method may be used. For example, methods exist that calculatework of breathing from sensors attached to the body to detect neural ormuscular activity as well as methods that determine a work of breathingbased on respiratory flow, respiratory pressure or a combination of bothflow and pressure.

In a PA breath type, the patient's work of breathing, the elastic workof breathing component, and/or the resistive WOB component may beestimated by inputting measurements from various sensors into thebreathing algorithms. Typically, none of the instantaneous inspiratorypressure, the instantaneous flow, or the resulting volume are set by theclinician. Because the PA breath type harmoniously links the ventilatorto the patient, the patient effectively “drives” the ventilator. Byappropriately setting the value of the proportionality (% support orsupport setting) control, the clinician may effectively partition thetotal work of breathing between the patient and the ventilator.

The DEA breath type delivers inspiration and expiration duringventilation of a spontaneously breathing patient based on monitoredneural respiratory output. Similar to the PA breath type, the DEA breathtype utilizes the patient's own respiratory demand or work of breathingto determine the level of assistance to provide the patient. The neuralrespiratory output, which the act of breathing depends on, is the resultof a rhythmic discharge from the center of brain. The discharge iscarried to the diaphragm muscles cells via the phrenic nerve causing thediaphragm muscles to contract. The contraction of diaphragm musclescauses the lungs to expand dropping pressure in the airways of the lungsto provide an inflow of air into the lungs.

The neural output is the captured electrical activity of the diaphragm(Edi). The Edi is then fed to the ventilator and used by the ventilatorto assist the patient's breathing. Because the ventilator and thediaphragm are triggered utilizing the same signal, the mechanicalcoupling between the ventilator and the diaphragm is almostinstantaneous.

However, if a patient becomes fatigued, the patient work of breathingmay sharply decrease. In positive feedback breath types, support iswithdrawn as the patient decreases his or her work of breathing.Therefore, the patient receives less support as the patient become morefatigued, which may cause the patient's fatigue to worsen.

Current ventilators do not monitor, measure and/or estimate the fatigueof a patient. Patient fatigue could result in longer ventilation timesand worsening of the patient's condition. Accordingly, the systems andmethods disclosed herein detect patient fatigue. In further embodiments,the systems and method disclosed herein display a fatigue notificationbased on a detected patient fatigue. In additional embodiments, thesystems and methods disclosed herein automatically change parametersbased on a detected patient fatigue. The term “parameter(s)” as usedherein refers to any variable(s) that can be input into the ventilator,monitored by the ventilator, determined by the ventilator, implementedby the ventilator, and/or selected by the ventilator. In someembodiments, after an automatic change in parameters, the systems andmethods disclosed herein may check to confirm mitigation of the detectedfatigue.

Further, patients that are ventilated for an extended period of time ina mandatory mode of ventilation may develop diaphragmatic weakness. Thenon-use of the diaphragm for the extended period of time may lead todiaphragm atrophy causing the diaphragmatic weakness or a predilectionfor developing fatigue. A mandatory mode delivers mandatory breaths to apatient based on a set respiratory rate. During a mandatory mode ofventilation, the patent cannot influence when inspiration or exhalationoccurs. Accordingly, the systems and methods disclosed herein providethe diaphragm with exercise intermittently during the mandatory mode ofventilation. The diaphragm is provided with exercise by switching fromthe mandatory mode of ventilation to a spontaneous mode of ventilationafter a set time period. During a spontaneous mode of ventilation,inspiration and/or exhalation is delivered upon the detection ofinspiratory and/or expiratory effort by the patient based on a triggertype. However, for safety measures, inspiration and exhalation may bedelivered after a predetermined amount of time passes to insure that thepatient receives breathing gas in the event the patient stops making orthe patient does not make any inspiratory and/or expiratory patientefforts. This exercise period expires after a predetermined exercisetime and/or if no inspiratory triggers are detected by the spontaneousmode of ventilation during the excise period. Further, the exerciseperiod expires if patient fatigue is detected. Additionally, theexercise period expires if a trend towards patient fatigue is detected.When the exercise period expires, the ventilator is switched back to thepreviously utilized mandatory mode of ventilation.

In some embodiments, a patient's diaphragm may develop weakness duringan assist/control mode, because the ventilator may still be performingthe bulk of the work for the patient during ventilation. Accordingly,the systems and methods disclosed herein may also provide the diaphragmwith exercise intermittently during the assist/control mode ofventilation. The diaphragm is provided with exercise by switching fromthe assist/control mode of ventilation to a spontaneous mode ofventilation after a set time period.

FIG. 1 is a diagram illustrating an embodiment of an exemplaryventilator 100 connected to a human patient 150. Ventilator 100 includesa pneumatic system 102 (also referred to as a pressure generating system102) for circulating breathing gases to and from patient 150 via theventilation tubing system 130, which couples the patient 150 to thepneumatic system 102 via an invasive (e.g., endotracheal tube, as shown)or a non-invasive (e.g., nasal mask) patient interface 180.

Ventilation tubing system 130 (or patient circuit 130) may be a two-limb(shown) or a one-limb circuit for carrying gases to and from the patient150. In a two-limb embodiment, a fitting, typically referred to as a“wye-fitting” 170, may be provided to couple a patient interface 180 (asshown, an endotracheal tube) to an inspiratory limb 132 and anexpiratory limb 134 of the ventilation tubing system 130.

Pneumatic system 102 may be configured in a variety of ways. In thepresent example, pneumatic system 102 includes an expiratory module 108coupled with the expiratory limb 134 and an inspiratory module 104coupled with the inspiratory limb 132. Compressor 106 or other source(s)of pressurized gases (e.g., air, oxygen, and/or helium) is coupled withinspiratory module 104 and the expiratory module 108 to provide a gassource for ventilatory support via inspiratory limb 132.

The inspiratory module 104 is configured to deliver gases to the patient150 according to prescribed ventilatory settings. In some embodiments,inspiratory module 104 is configured to provide ventilation according tovarious breath types, e.g., volume-control (VC), pressure-control (PC),volume support (VS), pressure support (PS), avolume-targeted-pressure-control (VC+), TC, DEA, PA, or via any othersuitable breath types.

The expiratory module 108 is configured to release gases from thepatient's lungs according to prescribed ventilatory settings.Specifically, expiratory module 108 is associated with and/or controlsan expiratory valve for releasing gases from the patient 150.

The ventilator 100 may also include one or more sensors 107communicatively coupled to ventilator 100. The sensors 107 may belocated in the pneumatic system 102, ventilation tubing system 130,and/or on the patient 150. The embodiment of FIG. 1 illustrates a sensor107 in pneumatic system 102.

Sensors 107 may communicate with various components of ventilator 100,e.g., pneumatic system 102, other sensors 107, processor 116,notification module 115, fatigue module 117, baseline module 118,indicator module 119, switch module 162, exercise module 160, oxygenmodule 164 and/or any other suitable components and/or modules. In oneembodiment, sensors 107 generate output and send this output topneumatic system 102, other sensors 107, processor 116 notificationmodule 115, fatigue module 117, baseline module 118, indicator module119, switch module 162, exercise module 160, oxygen module 164 and/orany other suitable components and/or modules. Sensors 107 may employ anysuitable sensory or derivative technique for monitoring one or moreparameters associated with the ventilation of a patient 150. Sensors 107may detect changes in parameters indicative of patient triggering, forexample. Sensors 107 may be placed in any suitable location, e.g.,within the ventilatory circuitry or other devices communicativelycoupled to the ventilator 100. Further, sensors 107 may be placed in anysuitable internal location, such as, within the ventilatory circuitry orwithin components or modules of ventilator 100. For example, sensors 107may be coupled to the inspiratory and/or expiratory modules fordetecting changes in, for example, circuit pressure and/or flow. Inother examples, sensors 107 may be affixed to the ventilatory tubing ormay be embedded in the tubing itself. According to some embodiments,sensors 107 may be provided at or near the lungs (or diaphragm) fordetecting a pressure in the lungs. Additionally or alternatively,sensors 107 may be affixed or embedded in or near wye-fitting 170 and/orpatient interface 180. Indeed, any sensory device useful for monitoringchanges in measurable parameters during ventilatory treatment may beemployed in accordance with embodiments described herein.

As should be appreciated, with reference to the Equation of Motion,parameters are highly interrelated and, according to embodiments, may beeither directly or indirectly monitored. That is, parameters may bedirectly monitored by one or more sensors 107, as described above, ormay be indirectly monitored or estimated by derivation according to theEquation of Motion.

The pneumatic system 102 may include a variety of other components,including mixing modules, valves, tubing, accumulators, filters, etc.Controller 110 is operatively coupled with pneumatic system 102, signalmeasurement and acquisition systems, and an operator interface 120 thatmay enable an operator to interact with the ventilator 100 (e.g., changeventilator settings, select operational modes, view monitoredparameters, etc.).

In one embodiment, the operator interface 120 of the ventilator 100includes a display 122 communicatively coupled to ventilator 100.Display 122 provides various input screens, for receiving clinicianinput, and various display screens, for presenting useful information tothe clinician. In one embodiment, the display 122 is configured toinclude a graphical user interface (GUI). The GUI may be an interactivedisplay, e.g., a touch-sensitive screen or otherwise, and may providevarious windows and elements for receiving input and interface commandoperations. Alternatively, other suitable means of communication withthe ventilator 100 may be provided, for instance by a wheel, keyboard,mouse, or other suitable interactive device. Thus, operator interface120 may accept commands and input through display 122. Display 122 mayalso provide useful information in the form of various ventilatory dataregarding the physical condition of a patient 150. The usefulinformation may be derived by the ventilator 100, based on datacollected by a processor 116, and the useful information may bedisplayed to the clinician in the form of graphs, wave representations,pie graphs, text, or other suitable forms of graphic display. Forexample, patient data may be displayed on the GUI and/or display 122.Additionally or alternatively, patient data may be communicated to aremote monitoring system coupled via any suitable means to theventilator 100.

Controller 110 may include memory 112, one or more processors 116,storage 114, and/or other components of the type commonly found incommand and control computing devices.

Controller 110 may further include a notification module 115, fatiguemodule 117, baseline module 118, indicator module 119, switch module162, exercise module 160, and/or oxygen module 164 configured to delivergases to the patient 150 according to prescribed breath types asillustrated in FIG. 1. In alternative embodiments, the notificationmodule 115, fatigue module 117, baseline module 118, indicator module119, switch module 162, exercise module 160, and/or oxygen module 164may be located in other components of the ventilator 100, such as thepressure generating system 102 (also known as the pneumatic system 102).

The memory 112 includes non-transitory, computer-readable storage mediathat stores software that is executed by the processor 116 and whichcontrols the operation of the ventilator 100. In an embodiment, thememory 112 includes one or more solid-state storage devices such asflash memory chips. In an alternative embodiment, the memory 112 may bemass storage connected to the processor 116 through a mass storagecontroller (not shown) and a communications bus (not shown). Althoughthe description of computer-readable media contained herein refers to asolid-state storage, it should be appreciated by those skilled in theart that computer-readable storage media can be any available media thatcan be accessed by the processor 116. That is, computer-readable storagemedia includes non-transitory, volatile and non-volatile, removable andnon-removable media implemented in any method or technology for storageof information such as computer-readable instructions, data structures,program modules or other data. For example, computer-readable storagemedia includes RAM, ROM, EPROM, EEPROM, flash memory or other solidstate memory technology, CD-ROM, DVD, or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to store thedesired information and which can be accessed by the computer.

In some embodiments, the inspiratory module 104 receives a breath typefrom operator selection. In some embodiments, the inspiratory module 104receives a breath type based on ventilator selection. In someembodiments, the breath type is a positive feedback breath type, such asa DEA breath type, TC breath type, or a PA breath type. With positivefeedback breath types, the amount of support provided by the ventilatoris proportional to the monitored patient's work of breathing. However,if a patient becomes fatigued, the patient may decrease their work ofbreathing. In positive feedback breath types, support is withdrawn asthe patient decreases his or her work of breathing. Therefore, thepatient receives less support as the patient become more fatigued, whichmay cause the patient's fatigue to worsen. Accordingly, a basal level ofpressure support may be set. The basal level of pressure support is aset pressure, pressure level, or support setting that provides theminimum amount of pressure support that the positive feedback breathtype delivers regardless of the patient's WOB. Accordingly, the basallevel of pressure support limits the positive feedback algorithm fromreducing support beyond a predetermined threshold during the breathtype.

In other embodiments, the breath type is a VC, PC, PS, VS, or VC+ breathtype. In some embodiments, a negative feedback breath type is utilized.A negative feedback breath type as utilized herein refers to a breathtype that provides support to the patient based inversely on the amountof WOB detected. Accordingly, the larger the patient's WOB the moresupport the ventilator provides during a negative feedback breath type.For example, a VS breath type and a VC+ breath type are negativefeedback breath types.

The baseline module 118 determines a baseline for one or more fatigueindicators. As used herein, the “baseline” designates a normal level ordesired level of the fatigue indicator for the patient. The fatigueindicator is any suitable parameter for providing an indication ofpatient fatigue. In an alternative embodiment, the fatigue indicator isa fatigue metric. The fatigue metric is any suitable function of two ormore fatigue indicators. For example, the fatigue metric may add,subtract, divide, and/or multiply two or more fatigue indicators. Thefatigue metric may be any suitable mathematical relationship between twoor more fatigue indicators for determining patient fatigue.

In some embodiments, at least one of the following parameters may beutilized as the fatigue indicator: WOB, partial pressure of carbondioxide in the blood (PaCO₂), the volume of carbon dioxide (VCO₂)produced by the patient 150, electromyography (EMG) of a respirationaccessory muscle, E_(di), measurement of the respiratory drive asindicated by the occlusion pressure of the airway at 100 ms (P_(0.1)),diaphragmatic position, P_(di), maximal transdiaphragmatic pressure(P_(di,max)), maximal inspiration pressure (P_(i,max)), cardiac output,velocity of muscle shortening, V_(t), diaphragm movement, esophagealpressure (P_(esoph)), P_(di) Maximum Relaxation Rate, estimatedinspiratory muscle pressure (P_(mus)) Maximum Relaxation Rate, abdominaland/or rib cage muscle contractions, paradoxical breathing, exhaledalveolar volume (V_(e alv)), respiration rate, bispectral index level ofsedation (BIS LOS), RSBI, tidal volume divided by inspiration time(V_(t)/T_(i)), diaphragm pressure divided by maximal diaphragm pressure(P_(di)/P_(di max)), inspiration time divided by total time of thebreath cycle (T_(i)/T_(tot)), dead space ventilation volume divided bytidal volume (V_(d)/V_(t)), pressure time index (P_(tid) or(P_(di)/P_(di max))/(T_(i)/T_(tot))), inspiration time divided by totaltime of the breath cycle divided by diaphragm pressure divided bymaximal diaphragm pressure (T_(i)/T_(tot)/P_(di)/P_(dimax)), respirationmuscle pressure divided EMG integral, the captured electrical activityof the phrenic nerve (E_(phr)), oxygen saturation level of the blood(SpO₂), minute volume (MV), and P_(mus). This list exemplary only and isnot meant to limit the disclosure.

In some embodiments, the fatigue indicator is taken directly from sensoroutput. In other embodiments, the fatigue indicator is derived (whichincludes estimated) from sensor output. In some embodiments, anindicator module 119 derives the fatigue indicator from sensor output.The indicator module 119 may be a separate component or may be a part ofthe baseline module 118, fatigue module 117, controller 110, and/orpneumatic system 102. For example, RSBI is respiratory rate divided byV_(t). Accordingly, in some embodiments, the fatigue module 117 derivesthe RSBI by dividing the measured flow by the measured V_(t), which areboth received as sensor output.

In some embodiments, the fatigue indicator is a work of breathing (WOB),which may be derived by the indicator module 119. In this embodiment,the indicator module 119 receives sensor output from one or more sensors107. The indicator module 119 derives (which includes estimating) thepatients work of breathing from the sensor output. In some embodiments,the derived work of breathing is calculated by entering the sensoroutput into the Equation of Motion. In other embodiments, the WOB isderived by the indicator module 119 by inputting various measurements(also known as sensor output) from various sensors into breathingalgorithms. In some embodiments, the sensor output is monitoredinspiratory flow and/or net flow. In other embodiments, the indicatormodule 119 estimates at least one of resistance, elastance, and/orcompliance from the sensor output in order to derive the WOB of thepatient 150. However, the indicator module 119 may utilize any knownsystems or methods for calculating a WOB of the patient 150 from sensoroutput. For example, methods exist that calculate work of breathing fromsensors 107 attached to the body to detect neural or muscular activityas well as methods that determine a work of breathing based onrespiratory flow, respiratory pressure or a combination of both flow andpressure.

In some embodiments, the baseline module 118 determines a baseline for afatigue indicator based on input from a clinician. For example, theclinician may enter the desired baseline for the patient. This allowsthe clinician to determine the desired baseline for a fatigue indicator.The clinician may take into account the patient's history, diseasestate, sex, and other factors when determining the baseline for afatigue indicator for a patient.

In an alternative embodiment, the baseline module 118 determines abaseline for fatigue indicators by averaging sensor output for each ofthe fatigued indicators for a predetermined amount of time. In someembodiments, the sensors 107 monitor the parameters every computationalcycle (e.g., 2 milliseconds, 5 milliseconds, 10 milliseconds, etc.). Inother embodiments, the sensors 107 monitor the parameters after apredetermined number of breaths (e.g., 1 breath, 2 breaths, 3 breaths,etc.). In other embodiments, the sensors 107 monitor the parametersafter a predetermined set sensor time period (e.g., 1 second, 2 seconds,30 seconds, 1 minute, 5 minutes, etc.). Accordingly, the baseline module118 adds the set of measurements or sensor output generated by therepeated sensor measurements for the predetermined amount of time andthen divides the total by the number of measurements taken to determinethe baseline. The predetermined time period may be any suitable amountof time for determining a normal or baseline parameter value for thepatient 150. In some embodiments, the predetermined amount of time is 10minutes, 30 minutes, 45 minutes, 1 hour, 1.5 hours, 2 hours, 6 hours, 12hours, or 24 hours.

In further, embodiments, some fatigue parameters only exist in a finitenumber of states. Accordingly, for these fatigue indicators apredetermined state will be the baseline. These baselines may bepredetermined and automatically configured on the ventilator 100. Forexample, absence of paradoxical breathing may be a baseline.Accordingly, the presence of paradoxical breathing is a detected changefrom this baseline.

In some embodiment, the predetermined amount of time starts after theventilator 100 delivers a predetermined number of breaths (e.g., 1breath, 2 breaths, 3 breaths, 5 breaths, etc.) from the start ofventilation. In other embodiments, the predetermined amount of timebegins after a set start time, such as 1 minute after the beginning ofventilation, 5 minutes after the beginning of ventilation, 10 minutesafter the beginning of ventilation, 1 hour after the beginning ofventilation, or 3 hours after the beginning of ventilation. In furtherembodiments, the predetermined amount of time begins after the start ofa spontaneous mode of ventilation or after ventilator support has beenreduced.

For example, in some implementations, the following may be utilized asbaselines for the following fatigue indicators:

PaCO₂ is 38-42 mmHg;

PaCO₂ for patients with COPD 42-62 mmHg;

pH of 7.38-7.42;

VCO₂ of 180-200 mL/min;

VCO₂ of 2.5-3.5 mL/Kg/min;

P_(0.1) of 1-2 cmH₂O;

P_(di,max) is about 80 cmH₂O;

P_(i,max) is about 80 cmH₂O;

V_(t) is 5-6 mL/kg;

P_(esoph) is 3-5 cmH₂O;

no paradoxical breathing;

respiration rate is 12-16/min for adults;

RSBI is less than 40;

P_(di)/P_(di max) is around 5-10%;

T_(i)/T_(tot) is about 30%; and V_(d)/V_(t) is 0.2-0.3.

After the baseline has been determined by the baseline module 118, thebaseline module 118 determines a change in the fatigue indicators fromthe baseline based on the sensor output. A change is determined by thebaseline module 118 when the current sensor output or monitor fatigueparameter is not equivalent or substantially equivalent to the baseline.In some embodiments, a fatigue parameter is considered substantiallyequivalent to the baseline when the difference between the fatigueparameter and the baseline is less than 1%. In other embodiments, afatigue parameter is considered substantially equivalent to the baselinewhen the difference between the fatigue parameter and the baseline isless than 3%. In further embodiments, a fatigue parameter is consideredsubstantially equivalent to the baseline when the difference between thefatigue parameter and the baseline is less than 5%.

If the baseline module 118 determines a change in the fatigue indicatorsfrom the baseline, then the baseline module 118 sends the change to thefatigue module 117. If the baseline module 118 does not determine achange in the fatigue indicators from the baseline, then the baselinemodule 118 continues to monitor for a change in the fatigue indicatorsbased on the sensor output from the baseline.

The fatigue module 117 determines if a patient 150 is fatigued. Thefatigue module 117 determines if a patient 150 is fatigued by comparingthe change received from the baseline module 118 to a fatigue threshold.In some embodiments, the fatigue threshold is input by an operator. Inother embodiments, the fatigue threshold is determined by the ventilator100 based on known parameters, such as ideal body weight, height,weight, sex, breath type, support setting, tidal volume, etc. In someembodiments, the fatigue threshold is a detected rate of change in thefatigue indicator. This list exemplary only and is not meant to limitthe disclosure.

If the detected change breaches the fatigue threshold, the fatiguemodule 117 of the ventilator 100 determines that the patient 150 isfatigued. If the detected change does not breach the fatigue threshold,the fatigue module 117 of the ventilator 100 determines that the patient150 is not fatigued. In one example, the fatigue module 117 monitors aspecific fatigue indicator. In an alternative example, the fatiguemodule 117 monitors numerous fatigue indicators to determine if anychanges of the fatigue indicators breach their corresponding fatiguethreshold. In another example, the fatigue module 117 monitors numerousfatigue indicators to determine if change in a predetermined number or aselect group of the fatigue indicators breach their correspondingfatigue thresholds. For example, the fatigue module 117 of ventilator100 may monitor a specific fatigue indicator, such as Rapid ShallowBreathing Index (RSBI), or may monitor numerous fatigue indicators (suchas RSBI, electrical activity of the diaphragm (E_(di)), tidal volume(V_(t)), work of breathing (WOB), and transdiaphragmatic pressure(P_(di))) to determine if any, a predetermined number, or a select groupof fatigue indicators breach their corresponding fatigue thresholds.

The fatigue threshold is any suitable fatigue indicator threshold forproviding an indication of patient fatigue. In embodiments, the fatigueindicator threshold is a threshold for a fatigue metric. In someembodiments, as discussed above, the fatigue indicator threshold is adetected rate of change in a fatigue indicator and/or metric. In someembodiments, the fatigue threshold is at least one of the followingthresholds:

work of breathing decrease below the baseline;

work of breathing increases above the baseline followed by a decreasebelow the baseline;

PaCO₂ increases from the baseline;

VCO₂ decreases from the baseline;

EMG of an accessory muscle indicates use of the accessory muscle;

E_(di) decreases from the baseline;

P_(0.1) increases and then decreases from the baseline;

diaphragmatic position becomes flattened;

P_(di) decreases from the baseline;

P_(di,max) decreases from the baseline;

P_(i,max) decreases from the baseline;

cardiac output does not increase from the baseline with an increasingload,

velocity of muscle shortening decreases from the baseline;

EMG time domain decreases from the baseline;

EMG, frequency domain decreases from the baseline;

V_(t) decreases from the baseline;

diaphragm movement imaging shows reduced movement from the baseline;

P_(esoph) decreases from the baseline;

P_(di) Maximum Relaxation Rate decreases from the baseline;

P_(mus) Maximum Relaxation Rate decreases from the baseline;

alternating abdominal/rib cage muscle contractions occur or increase infrequency from the baseline;

V_(e alv) decreases from the baseline;

respiration rate increases followed by a decrease from the baseline;

BIS LOS is normal;

RSBI increases from the baseline;

V_(t)/T_(i) decreases from the baseline;

P_(di)/P_(di max) increases from the baseline;

T_(i)/T_(tot) increases from the baseline;

V_(d)/V_(t) increases from the baseline;

P_(tid) increases from the baseline;

T_(i)/T_(tot)/P_(di)/P_(dimax) increases from the baseline;

Respiration muscle pressure/EMG integral decreases from the baseline;

E_(di) increases while E_(phr) increases and P_(di) decreases from thebaseline;

P_(di,max) decreases from the baseline;

P_(i,max) decreases from the baseline;

E_(di) increases and at least one of a decrease in V_(t), a decrease inVCO₂, a decrease in SpO₂, an increase in P_(0.1), and a decrease in MVfrom the baseline occurs;

P_(mus) decreases and at least one of a decrease in V_(t), a decrease inVCO₂, a decrease in SpO₂, and a decrease in MV from the baseline occurs;

PaCO₂ increases from the baseline by at least 10 mmHg,

VCO₂ decrease from the baseline by more than 20%,

E_(di) decreases from the baseline by at least 25%,

E_(di) stays the same while the velocity of muscle shortening decreasesfrom the baseline;

P_(0.1) increases above 4 cm of H₂O and then decreases by at least 2 cmof H₂O,

P_(di) decreases by at least 10% from the baseline;

P_(di,max) decreases by at least 20% from the baseline;

P_(i,max) decreases by at least 20% from the baseline;

velocity of muscle shortening decreases by at least 25% from thebaseline;

EMG time domain is less than 50 uV;

EMG, frequency domain decreases by more than 20% from the baseline;

V_(t) is below 4 mL/kg;

P_(esoph) decreases by at least 10% from the baseline;

P_(di) Maximum Relaxation Rate decreases by at least 20% from thebaseline;

P_(mus) Maximum Relaxation Rate decreases by at least 20% from thebaseline;

presence of paradoxical breathing;

V_(e alv) decreases by at least 20% from the baseline;

respiration rate increases above 35 breaths a minute;

respiration rate increases by at least 25% from the baseline followed bya decrease;

RSBI increases above 105;

V_(t)/T_(i) decreases by 30% from the baseline;

P_(di)/P_(di max) is above 40% from the baseline;

T_(i)/T_(tot) is greater than 40% from the baseline;

V_(d)/V_(t) increases by 20% from the baseline;

V_(d)/V_(t) is greater than 40% from the baseline;

P_(tid) increases above 0.15; and

T_(i)/T_(tot)/P_(di)/P_(dimax) is greater than 40% from the baseline.

This list exemplary only and is not meant to limit the disclosure. Anysuitable thresholds for determining fatigue in a patient duringventilation may be utilized by the ventilator.

In additional embodiments, the fatigue module 117 may determine thelevel of fatigue detected. To determine the level of fatigue detected,the fatigue module 117 may weigh how much a fatigue threshold wasbreached, how many fatigue thresholds were breached, and/or a rate atwhich any breach is increasing. The ventilator 100 may utilize amathematical algorithm for weighing the above parameters to determinethe level of fatigue detected. In some embodiments, the fatigue module117 may list the patient fatigue as high, medium, or low. In otherembodiments, a fatigue index is determined by the fatigue module 117.The fatigue index may indicate the level of fatigue experience by thepatient. For example, the fatigue index may be a scale of 1-10 or 1-3.The higher the degree of patient fatigue, the higher the fatigue indexdetermined by the ventilator (1 may be the high end or 10 and 3 may bethe high end of the scale depending upon the desired index).Accordingly, in one embodiment where the fatigue module 117 detects ahigh level of fatigue, a fatigue index of 8 may be determined. Inanother embodiment, where the fatigue module 117 detects a medium levelof fatigue, a fatigue index of 5 or 2 may be determined. The listedfatigue indexes above are not meant to be limiting. Any suitableindication of a patient's fatigue level may be utilized by the fatiguemodule 117 as the fatigue index, including symbols, colors (i.e., red,yellow, and green to designate different fatigue levels), text, numbers,and/or animations.

In some embodiments, if patient fatigue is detected by the fatiguemodule 117, the fatigue module 117 communicates with the notificationmodule 115. The notification module 115 determines an appropriatenotification based on the information received from the fatigue module117. When patient fatigue is implicated, many clinicians may not beaware of adjustments to parameters that may reduce or eliminate fatigue.As such, upon detection of patient fatigue, the notification module 115may be configured to notify the clinician that patient fatigue isimplicated and/or to provide recommendations to the clinician formitigating patient fatigue. Accordingly, the notification message mayinclude a recommendation for mitigating patient fatigue. For example,notification module 115 may be configured to notify the clinician bydisplaying a notification on display 122 and/or within a window of theGUI. According to additional embodiments, the notification iscommunicated to and/or displayed on a remote monitoring systemcommunicatively coupled to ventilator 100. According to alternativeembodiments, the notification is any audio and/or visual notification.Alternatively, in an automated embodiment, the notification module 115communicates with a ventilator control system, such as the controller110 so that the recommendation may be automatically implemented tomitigate the patient fatigue.

In order to accomplish the various aspects of the notification messagedisplay, the notification module 115 may communicate with various othercomponents and/or modules. For instance, notification module 115 may bein communication with processor 116, fatigue module 117, baseline module118, indicator module 119, or any other suitable module or component ofthe ventilator 100. That is, notification module 115 may receive anindication that fatigue has been implicated by any suitable means. Inaddition, notification module 115 may receive information regarding oneor more parameters that implicated the presence of patient fatigue andinformation regarding the patient's ventilator settings and treatment.Further, according to some embodiments, the notification module 115 mayhave access to a patient's diagnostic information (e.g., regardingwhether the patient has ARDS, COPD, asthma, emphysema, or any otherdisease, disorder, or condition).

In some embodiments, notifications may be provided according to ahierarchical structure such that a notification may be initiallypresented in summarized form and, upon clinician selection, anadditional detailed notification may be displayed. According toalternative embodiments, a notification is initially presented without arecommendation and, upon clinician selection, a recommendation messageis displayed. Alternatively or additionally, the notificationsimultaneously displays a detection of patient fatigue with arecommendation message in any suitable format or configuration.

Specifically, according to some embodiments, the notification alerts theclinician as to the detection of a patient condition, a change inpatient condition, or an effectiveness of ventilator treatment. Forexample, the notification message determined by the notification module115 may alert the clinician that fatigue has been detected and theparameters that indicated the patient fatigue (i.e., WOB, RSBI, V_(t),E_(di), and etc.). The notification may further alert the clinicianregarding the particular breach or level of breach of the particularsparameter(s) that implicated patient fatigue (e.g., WOB, cardiac output,P_(di), VCO₂, etc.) For example, the notification may recite thatpatient fatigue is detected and then list the fatigue indicator thatindicated the patient fatigue.

In some embodiments, the notification recites the following messages:

fatigue detected;

fatigue warning;

fatigue implicated; and

fatigue notification.

In some embodiments, the notification may further recite the one or morefatigue indicator measurements that indicated the patient fatigue. Inother embodiments, the notification may also recite the one or morefatigue thresholds. In other embodiments, the level of fatigue isdisplayed in the notification. For example, the notification may list ahigh, medium, or low level of patient fatigue is detected. In otherembodiments, a fatigue index may be listed in the notification. Asdiscussed above the fatigue index may indicate the level of patentfatigue detected by the fatigue module 117. Further, any suitableindication of a patient's fatigue level may be displayed by thenotification module 115 as the fatigue index, including symbols, colors(i.e., red, yellow, and green to designate different fatigue levels),text, numbers, and/or animations.

Additionally, according to embodiments as discussed above, thenotification may provide various suggestions to the clinician foraddressing detected patient fatigue. In some embodiments, therecommendation includes any change in ventilation that provides thepatient with additional ventilation support. According to additionalembodiments, the notification may be based on the particularparameter(s) that implicated the patient fatigue. Additionally oralternatively, the recommendation may be based on current ventilatorsettings (e.g., breath type). Additionally or alternatively, therecommendation may be based on a diagnosis and/or other patientattributes. Further still, the recommendation may include a primaryrecommendation message and a secondary recommendation message. Forexample, the primary recommendation message may recite, “considerswitching breath types” and the secondary recommendation message mayrecite, “consider switching to a VC+ breath type.” In another example,the primary recommendation message may recite, “consider utilizing abasal level of pressure support in the PA breath” and the secondaryrecommendation may recite, “consider utilizing 5 cm H₂O as your basallevel of support.” In an additional example, the primary recommendationmessage may recite, “consider switching to invasive ventilation” and thesecondary recommendation may recite, “consider switching to a negativefeedback breath type.”

As discussed above, the basal level of pressure support limits thepositive feedback during a positive feedback breath type from reducingsupport beyond a predetermined threshold. Therefore, the patientreceives at least this minimal amount of pressure support when a basallevel of pressure support is utilized. Accordingly, the basal level ofpressure support may mitigate detected patient fatigue. The basal levelof pressure support may vary based on the patient. In some embodiments,the basal level of pressure support is at least 5 cm H₂O. In otherembodiments, the basal level of pressure support is at least 8 cm H₂O.

Notification module 115 may be responsible for generating a notificationvia any suitable method or system. For example, the notification may beprovided as a tab, banner, dialog box, or other similar type of display.Further, the notification may be provided along a border of thegraphical user interface, near an alarm display or bar, or in any othersuitable location. A shape and size of the notification may further beoptimized for easy viewing with minimal interference to other ventilatordisplays. The notification message may be further configured with acombination of icons and text such that the clinician may readilyidentify the message as a notification message.

The notification module 115 may be responsible for generating one ormore recommendations via any suitable systems or methods. The one ormore recommendations may provide suggestions and information regardingaddressing the detected patient fatigue. In some embodiments, the one ormore recommendations identifies the parameters that implicated thedetected condition, provides suggestions for adjusting the one or moreparameters to address the detected fatigue, provides suggestions forchecking ventilator equipment or patient position, and/or provides otherhelpful information. For example, if fatigue is implicated, thenotification may include one or more of the following recommendations:

consider switching to invasive ventilation;

consider switching to a negative feedback breath type;

consider switching to a PS, PC, VC, VC+, or VS breath type;

consider increasing ventilation support;

consider increasing a support setting in the PA breath type;

consider increasing a support setting in the DEA breath type;

consider increasing a support setting in a positive feedback breathtype;

consider increasing set respiratory rate;

consider utilizing a basal level of support in the PA breath type;

consider utilizing a basal level of support in the DEA breath type; and

consider utilizing a basal level of support in a positive feedbackbreath type.

As discussed above, in some embodiments, after patient fatigue isdetected by the fatigue module 117, the notification module 115recommends switching from non-invasive ventilation to invasiveventilation. Studies have shown that waiting too long before switchingfrom non-invasive ventilation to invasive patient ventilation when apatient is responding poorly to ventilation (e.g., detecting patientfatigue) has been linked to an increased mortality rate. Accordingly, ifpatient fatigue is detected, the notification module 115 may recommendswitching from a non-invasive ventilation (i.e., use of a nasal mask andother setting changes) to invasive ventilation (i.e. use of anendotracheal tube and other setting changes). However, since theventilators cannot automatically implement such a change, the clinicianbased on the patient, the patient's history, and measured parametersmust determine if switching from non-invasive ventilation to an invasiveventilation is warranted.

As discussed above, in an automated embodiment, the notification module115 communicates with a ventilator control system, such as thecontroller 110, so that the recommendation may be automaticallyimplemented to mitigate the patient fatigue. The automatedimplementation of the recommendation may be performed automatically bythe ventilator 100 or performed automatically upon user selection of anautomated response mode. In some embodiments, the notification module115 of the ventilator 100 automatically implements the recommendations.In other embodiments, any suitable ventilator component with a processorautomatically implements the recommendations. For example, if patientfatigue is detected during a positive feedback breath type, thenotification module 115 of ventilator 100 may automatically implement abasal level of pressure support. In an alternative embodiment, ifpatient fatigue is detected during a positive feedback breath type(e.g., PA), the notification module 115 of ventilator 100 automaticallyswitches to non-positive feedback breath type. For example, theventilator 100 may switch to a negative feedback breath type (e.g., VSor VC+) or to another breath type (e.g., VC, VS, and PC). In someembodiments, notification module 115 notifies the clinician of theautomated adjustment to account for detected patient fatigue. In oneembodiment, the notification module 115 of ventilator 100 displays anotification indicating that patient fatigue is detected and theautomated adjustment made to account for this fatigue. For example, ifpatient fatigue is detected during a positive feedback breath type, thenotification may recite, “fatigue detected” and “basal level of pressuresupport implemented to mitigate fatigue.” In another example, if patientfatigue is detected during a positive feedback breath type, thenotification may recite, “fatigue implicated” and “switched to a PCbreath type to mitigate fatigue.” This list is merely exemplary. Any ofthe above recommendations that are suitable for automatic implementationmay be automatically implemented by the ventilator after patient fatigueis detected by the ventilator.

In some embodiments, if a recommendation is automatically implemented bythe ventilator, the fatigue module 117 confirms that the detectedpatient fatigue was mitigated by the implemented response. In thisembodiment, the fatigue module 117 after a predetermined rest time thatbegins when the recommendation is implemented, re-measures from thegenerated sensor output the one or more changes in fatigue indicatorsthat previously breached a threshold to indicate the detected patientfatigue. In some embodiments, the predetermined rest time is severalminutes to a few hours. For example, the predetermined rest time isabout 30 minutes, 45 minutes, 1 hour, 1.25 hours, 1.5 hours, 1.75 hours,2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours,10 hours, 11 hours, or 12 hours. However, any suitable amount of time toprovide the patient with rest to mitigate fatigue may be utilized by theventilator 100. The implemented recommendation provides the patient withadditional ventilation support and thereby is allowing the patient torest during the predetermined rest time. The one or more changes infatigue indicators of the patient that breached a threshold to indicatethe patient's fatigue are referred to herein as “breached parameters.”The one or more changes in fatigue indicators of the patient determinedafter the predetermined rest time are referred to herein as “restedparameters.” For example, if a determined RSBI of the patient indicatedthe patient fatigue, then after the predetermined rest time the RSBI ofthe patient would be determined. The determined RSBI after thepredetermined rest time is the rested parameter. The RSBI determinedbefore the predetermined rest time that indicated the breach is thebreached parameter. In some embodiments, the ventilator settingsutilized to determine the ventilation of the patient, such as breathtype, are changed back to settings that were previously utilized duringthe detection of the patient fatigue before determining the breachedparameters. The settings are returned to the settings utilized duringfatigue detection to ensure that any difference between the restedparameters and the baseline cannot be attributed to the differentventilator settings utilized during ventilation of the patient at thetime of measurement.

The fatigue module 117 compares the rested parameters to the baseline.The fatigue module 117 determines if the implemented recommendationmitigated the determined fatigue based on the comparison of the restedparameters to the baseline. If the fatigue module 117 determines thatthe rested parameters have improved by a predetermined amount whencompared to the baseline, then the fatigue module 117 determines thatthe implemented recommendation mitigated the patient fatigue. However,if the fatigue module 117 determines that the rested parameters have notimproved by a predetermined amount when compared to the baseline, thenthe fatigue module 117 determines that the implemented recommendationdid not mitigate the patient fatigue.

In some embodiments, the rested parameter is considered to be improvedif the rested parameter improved by 50% or more when compared to thebaseline. In some embodiments, the rested parameter is considered to beimproved if the rested parameter improved by 80% or more when comparedto the baseline. In other embodiments, the rested parameter isconsidered to be improved if the rested parameter no longer breaches thepredetermined threshold for determining patient fatigue when compared tothe baseline. For example, if the rested parameters are a rested RSBI of85 and a rested spontaneous V_(t) is 5 mL/kg, then the fatigue module117 determines that the patient fatigue was mitigated by the implementedrecommendation because the rested parameters have improved so much thatthe rested parameters no longer breach the fatigue threshold whencompared to the baseline.

If the implemented recommendation, which provided the patient withadditional ventilator support in order to rest the patient, mitigatedthe fatigue of the patient, then the patient is confirmed to have beenfatigued. Accordingly, in some embodiments, if the fatigue module 117determines that the implemented recommendation did mitigate the fatigue,then the fatigue module 117 instructs the notification module 115 todisplay a notification relating to the mitigated fatigue.

The notification module 115 displays notifications relating to themitigated fatigue based on the instructions from the fatigue module 117.The notification includes a notification that the fatigue was fixed bythe implemented recommendation. The notification may further include anotice that the patient fatigue was the correct assessment, that theimplemented recommendation was sufficient to mitigate the patientfatigue, and/or that the patient's condition is improved. In someembodiments, the notification may further include one or morerecommendations for changing the level of ventilatory support for thepatient now that the patient is no longer fatigued. In furtherembodiments, the notification may further include a reference to therested parameters, the breached parameters, the baseline, and/or thepredetermined thresholds of the breached parameters. These notificationsinclude any of the features discussed above for a notification message,such as a hierarchical structure, display on a remote monitoring system,and/or a summarize format with recommendations offered upon selection.For example, the notification relating to the mitigated fatigue mayinclude:

Fatigue mitigated;

Consider switching to a positive feedback breath type;

Patient fatigue confirmed;

Fatigue reduced by at least 80%; and

etc.

If the implemented recommendation, which provided the patient withadditional ventilator support in order to rest the patient, did notmitigate the fatigue, then the patient may not have been fatigued, theimplemented recommendation may not have been sufficient to mitigate thepatient fatigue, and/or the patient's condition may have deteriorated.Accordingly, in some embodiments, if the fatigue module 117 determinesthat the implemented recommendation did not mitigate the fatigue, thenthe fatigue module 117 instructs the notification module 115 to displaya notification relating to the unmitigated fatigue.

The notification module 115 displays notification relating to theunmitigated fatigue based on the instructions from the fatigue module117. The notification includes a notification that the fatigue was notfixed by the implemented recommendation. The notification may furtherinclude a notice that the patient fatigue was an incorrect assessment,that the implemented recommendation was insufficient to mitigate thepatient fatigue, and/or that the patient's condition may havedeteriorated. In some embodiments, the notification may further includeone or more recommendations for dealing with the unmitigated fatigue. Infurther embodiments, the notification may further include a reference tothe rested parameters, the breached parameters, and/or the predeterminedthresholds of the breached parameters. These notifications include anyof the features discussed above for a notification message, such as ahierarchical structure, display on a remote monitoring system, and/or asummarize format with recommendations offered upon selection. Forexample, the notification relating to the unmitigated fatigue mayinclude:

Fatigue treatment failed;

Patient condition deteriorating—Fatigue unmitigated;

Warning patient not responding to fatigue treatment;

Warning patient not fatigued, consider checking other causes of thechange in the fatigue indicator;

Warning fatigue detected in error, consider checking other parameters todetermine the cause of the patient's detected negative condition; and

etc.

In some embodiments, the ventilator 100 includes an exercise module 160and a switch module 162. In these embodiments, the ventilator 100 mayfurther include an oxygen module 164. As discussed above, patients thatare ventilated for an extended period of time in a mandatory mode ofventilation may develop diaphragmatic weakness. The non-use of thediaphragm for the extended period of time during the mandatory mode maylead to diaphragm atrophy causing the diaphragmatic weakness or fatigue.Accordingly, the exercise module 160 and the switch module 162 allow theventilator 100 to exercise the diaphragm of the patient 150 in anattempt to mitigate or prevent the diaphragm atrophy and/or weakness.

In some embodiments, the switch module 162 switches from a set mandatorymode of ventilation to a spontaneous mode of ventilation after apredetermined amount of time expires or after a specific event, such asa predetermined number of breaths, inspirations, or cycle. In someembodiments, the switch module 162 is activated upon clinician input. Inother embodiments, the switch module 162 is activated after a patienthas been ventilated based on a mandatory mode of ventilation for acertain amount of time or after a predetermined number of breaths. Thecertain amount of mandatory mode time may be input by the clinician orpredetermined by the ventilator. In some embodiments, a patient'sdiaphragm may develop weakness during an assist/control mode, becausethe ventilator may still be performing the bulk of the work for thepatient during ventilation. Accordingly, in this embodiment the switchmodule 162 switches from a set assist/control mode of ventilation to aspontaneous mode of ventilation after a predetermined amount of timeexpires or after a specific event, such as a predetermined number ofbreaths, inspirations, or cycle. If the switch module 162 is notactivated, the switch module 162 does not switch from the set mandatorymode of ventilation to a spontaneous mode of ventilation when a timeperiod expires or a set event occurs.

The predetermined amount of mandatory mode time begins with the start ofthe mandatory mode during ventilation. The start of the mandatory modeof ventilation is any time the ventilator is switched into a mandatorymode of ventilation from a different mode or at the beginning ofventilation just after the ventilator is turned on. In some embodiments,the predetermined amount of mandatory mode time (also referred to as astandard time period) is about 30 minutes, 45 minutes, 60 minutes, 75minutes, 90 minutes, 105 minutes, or 120 minutes. The mandatory modetime may be any suitable amount of time that provides an intermittentspontaneous mode often enough to prevent or mitigate diaphragm atrophyor weakness.

Several different breath types may be utilized during the mandatory modeof ventilation. In some embodiments, a pressure control (PC) breath typeis utilized during the mandatory mode of ventilation. In otherembodiments, a volume control (VC) breath type is utilized during themandatory mode of ventilation. In further embodiments, avolume-controlled-pressure-targeted (VC+) breath type is utilized duringthe mandatory mode of ventilation.

The VC breath type allows a clinician to set a respiratory rate and toselect a volume to be administered to a patient during a mandatorybreath. When using VC, a clinician sets a desired tidal volume, flowwave form shape, and an inspiratory flow rate or inspiratory time. Thesevariables determine how much volume of gas is delivered to the patientand the duration of inspiration during each mandatory breath inspiratoryphase. The mandatory breaths are administered according to the setrespiratory rate.

For VC, when the delivered volume is equal to the prescribed tidalvolume, the ventilator may initiate exhalation. Exhalation lasts fromthe time at which prescribed volume is reached until the start of thenext ventilator mandated inspiration. This exhalation time is determinedby the respiratory rate set by the clinician and any participation abovethe set rate by the patient. Upon the end of exhalation, another VCmandatory breath is given to the patient.

During VC, delivered volume and flow waveforms may remain constant andmay not be affected by variations in lung or airway characteristics.Alternatively, pressure readings may fluctuate based on lung or airwaycharacteristics. According to some embodiments, the ventilator maycontrol the inspiratory flow and then derive volume based on theinspiratory flow and elapsed time.

The PC breath type allows a clinician to select a pressure to beadministered to a patient during a mandatory breath. When using the PCbreath type, a clinician sets a desired pressure, inspiratory time, andrespiratory rate for a patient. These variables determine the pressureof the gas delivered to the patient during each mandatory breathinspiration. The mandatory breaths are administered according to the setrespiratory rate.

For the PC breath type, when the inspiratory time is equal to theprescribed inspiratory time, the ventilator may initiate exhalation.Exhalation lasts from the end of inspiration until the next inspiration.Upon the end of exhalation, another PC mandatory breath is given to thepatient.

During PC breaths, the ventilator may maintain the same pressurewaveform at the mouth, regardless of variations in lung or airwaycharacteristics, e.g., respiratory compliance and/or respiratoryresistance. However, the volume and flow waveforms may fluctuate basedon lung and airway characteristics.

The VC+ breath type is a combination of volume and pressure controlbreath types that may be delivered to a patient as a mandatory breath.In particular, VC+ may provide the benefits associated with setting atarget tidal volume, while also allowing for variable flow.

As may be appreciated, when resistance increases and/or compliancedecreases it becomes more difficult to pass gases into and out of thelungs, decreasing flow. For example, when a patient is intubated, i.e.,having either an endotracheal or a tracheostomy tube in place,resistance may be increased as a result of the smaller diameter of thetube over a patient's natural airway. In addition, increased resistancemay be observed in patients with obstructive disorders, such as COPD,asthma, etc. Higher resistance and/or lower compliance may necessitate,inter alia, a higher inspiratory pressure setting for delivering aprescribed pressure or volume of gases.

Unlike VC, when the set inspiratory time is reached, the ventilator mayinitiate exhalation. Exhalation lasts from the end of inspiration untilthe beginning of the next inspiration. The expiratory time (T_(E)) isbased on the respiratory rate set by the clinician. Upon the end ofexhalation, another VC+ mandatory breath is given to the patient. Bycontrolling target tidal volume and allowing for variable flow, VC+allows a clinician to maintain the volume while allowing the flow andpressure targets to fluctuate.

Several different breath types may be utilized during the spontaneousmode of ventilation. In some embodiments, a continuous positive airwaypressure (CPAP) breath type is utilized during the spontaneous mode ofventilation. In other embodiments, a Bilevel breath type is utilizedduring the spontaneous mode of ventilation. While Bilevel provides amixed mode of ventilation (mandatory and spontaneous breaths), theBiLevel breath type allows a patient to spontaneously trigger breathsabove different provided pressures. In further embodiments, volumesupport (VS), pressure support (PS), proportional assist (PA), or tubecompensation (TC) is utilized during the spontaneous mode ofventilation.

The ventilator during a CPAP breath type maintains a continuous level ofpositive airway pressure throughout a breath. The CPAP breath type isfunctionally similar to PEEP, except that PEEP is an applied pressureagainst exhalation and CPAP is a pressure applied during inspiration andexhalation. Further, no additional pressure above the level of CPAP isprovided. The CPAP breath type is utilized during a spontaneous mode ofventilation because a patient must initiate all of his or her breathsduring the CPAP breath type.

During a Bilevel breath type, the mandatory breaths are alwayspressure-controlled and spontaneous breaths can be pressure-supported,PA, VS, or tube compensated. BiLevel establishes two levels of positiveairway pressure, similar to having two levels of PEEP. Cycling betweenthe two levels can be triggered by BiLevel timing settings or by patienteffort. The two levels of PEEP may be referred to as PEEP_(HIGH) andPEEP_(LOW). At each level the Bilevel breath has a way to cycle from onePEEP level to the other, to respond to spontaneous inspirations, tocalculate pressure support, to synchronize transitions between PEEPlevels with the patient's breathing, and to transition into and out ofBiLevel mode. Over the course of a breath interval, BiLevel cycles theventilator between the two PEEP levels (PEEP_(HIGH) and PEEP_(LOW)). Thedurations of PEEP_(HIGH) and PEEP_(LOW) are defined by the variablestime high (T_(HIGH)) and a time low (T_(LOW)). BiLevel attempts tosynchronize the transition from one PEEP level to the other with thepatient's breathing pattern.

The actual durations of T_(HIGH) and T_(LOW) vary according to whetheror not the patient makes any spontaneous inspiratory efforts. To improveventilator-patient synchrony, BiLevel allows T_(HIGH) and T_(LOW) to beextended to prevent transitions to PEEP_(LOW) during inspiration and toPEEP_(HIGH) during early exhalation. If the patient breathesspontaneously at either PEEP level, the monitored respiratory rateincreases. If the patient triggers only transitions from one PEEP levelto the other, the monitored respiratory rate can increase or decrease.If the patient does not trigger any transitions between PEEP levels anddoes not breathe spontaneously, the monitored respiratory rate equalsthe set rate, and the cycle interval equals 60/f.

Further, during a Bilevel breath type, the spontaneous breaths can beaugmented with pressure support. The Bilevel breath type allows theoperator to add pressure support to breaths taken at either pressurelevel to offset patient circuit resistance or unload inspiratory work byaugmenting tidal volume. If the pressure support level is set higherthan PEEP_(HIGH), the upper portion of the PS breath actually appearsabove the PEEP_(HIGH) level. The PS breath can also be seen duringT_(L). Note that when no pressure support is set, a spontaneous effortreceives a predetermined amount of pressure, such as 1.5 cmH₂O ofpressure, to reduce the work of breathing.

The VS breath type is utilized in the present disclosure as aspontaneous breath. VS is generally used with a triggering(spontaneously breathing) patient when the patient is ready to be weanedfrom a ventilator or when the patient cannot do all of the work ofbreathing on his or her own. When the ventilator senses patientinspiratory effort, the ventilator delivers a set tidal volume duringinspiration. The tidal volume may be set and adjusted by the clinician.The patient controls the rate, inspiratory flow, and has some controlover the inspiratory time. The ventilator then adjusts the pressure overseveral breaths to achieve the set tidal volume. When the machine sensesa decrease in flow, or inspiration time reaches a predetermined limit,the ventilator determines that inspiration is ending. When delivered asa spontaneous breath, exhalation in VS lasts from a determination thatinspiration is ending until the ventilator senses a next patient effortto breathe.

The PS breath type is a form of assisted ventilation and is utilized inthe present disclosure during a spontaneous breath. The PS breath typeis a patient triggered breath and is typically used when a patient isready to be weaned from a ventilator or for when patients are breathingspontaneously but cannot do all the work of breathing on their own. Whenthe ventilator senses patient inspiratory effort, the ventilatorprovides a constant pressure during inspiration. The pressure may be setand adjusted by the clinician. The patient controls the rate,inspiratory flow, and to an extent, the inspiratory time. The ventilatordelivers the set pressure and allows the flow to vary. When the machinesenses a decrease in flow, or determines that inspiratory time hasreached a predetermined limit, the ventilator determines thatinspiration is ending. Exhalation in the PS breath type lasts from adetermination that inspiration is ending until the ventilator senses apatient effort to breathe.

The PA breath type, as discussed above, refers to a type of ventilationin which the ventilator acts as an inspiratory amplifier that providespressure support based on the patient's WOB and is describe in furtherdetail above.

A TC breath type is similar to the PA breath type. The TC breath typedelivers breathing gases to a spontaneously-breathing patient with theobjective of reducing the patient's work of breathing imposed by anartificial airway. During a TC breath type, the ventilator compensatesfor the load associated with breathing through an endotracheal ortracheostomy tube. The TC breath type calculates a tube resistance basedon the tube type (endotracheal or tracheostomy) and the tube's internaldiameter, which are settings input by the clinician. A tube compensationpressure is then calculated by the ventilator during the TC breath typeas a function of the patient's monitored flow, the calculated tuberesistance, and a percent support setting (also known as supportsetting) input by the clinician. During inhalation, the ventilatorduring the TC breath type delivers the tube compensation pressure plus aset PEEP to the patient airway. Upon reaching an expiration sensitivitysetting (or other cycling criteria), the ventilator during the TC breathtype initiates exhalation. As with other pressure-based breath types,the ventilator during the TC breath type does not target a set tidalvolume or flow pattern.

The exercise module 160 monitors the patient during the spontaneous modeof ventilation based on sensor output. In some embodiments, the exercisemodule 160 switches from the spontaneous mode of ventilation back to theset mandatory mode of ventilation when the first of the following eventsoccur during the spontaneous mode based on the sensor output: (1)detection of patient fatigue and (2) a predetermined exercise periodexpires and no inspiratory triggers are detected during the exerciseperiod. In other embodiments, the exercise module 160 switches from thespontaneous mode of ventilation back to the set mandatory mode ofventilation when the first of the following events occur during thespontaneous mode based on the sensor output: (1) detection of patientfatigue and (2) a predetermined exercise period expires. In furtherembodiments, the exercise module 160 switches from the spontaneous modeof ventilation back to the set mandatory mode of ventilation when thefirst of the following events occur during the spontaneous mode based onthe sensor output: (1) detection of a trend towards patient fatigue and(2) a predetermined exercise period expires and no inspiratory triggersare detected during the exercise period. In other embodiments, theexercise module 160 switches from the spontaneous mode of ventilationback to the set mandatory mode of ventilation when the first of thefollowing events occur during the spontaneous mode based on the sensoroutput: (1) detection of a trend towards patient fatigue and (2) apredetermined exercise period expires.

The detection of patient fatigue by the ventilator 100 is discussedabove. The ventilator utilizes the fatigue module 117 and baselinemodule 118 as described above to detect patient fatigue. Further, theventilator 100 may further utilize the indicator module 119 to detectpatient fatigue as described above. In some embodiments, at least one ofthe fatigue indicators utilized to detect fatigue is WOB. The detectionof a trend toward patient fatigue is determined by the ventilator 100when two or more consecutive changes of a fatigue indicator receivedfrom the baseline module 118 that do not breach the fatigue thresholdget consecutively closer to breaching the fatigue threshold.

There are several different trigger types or systems and/methodsutilized by the ventilator 100 for detecting patient triggers and/orcycles. In some embodiments, the trigger type for detecting patienteffort may be selected or input by an operator. In some embodiments, thetrigger type is automatically selected by the ventilator. Any suitabletype of triggering detection for determining a patient trigger may beutilized by the ventilator, such as nasal detection, diaphragmdetection, and/or brain signal detection. Further, the ventilator maydetect patient triggering via a pressure-monitoring method, aflow-monitoring method, direct or indirect measurement of neuromuscularsignals, or any other suitable method. Sensors 107 suitable for thisdetection may include any suitable sensing device as known by a personof skill in the art for a ventilator. In addition, the sensitivity ofthe ventilator to changes in pressure and/or flow may be adjusted suchthat the ventilator may properly detect the patient effort, i.e., thelower the pressure or flow change setting the more sensitive theventilator may be to patient triggering.

According to embodiments, a pressure-triggering method may involve theventilator monitoring the circuit pressure, as described above, anddetecting a slight drop in circuit pressure. The slight drop in circuitpressure may indicate that the patient's respiratory muscles, arecreating a slight negative pressure gradient between the patient's lungsand the airway opening in an effort to inspire. The ventilator mayinterpret the slight drop in circuit pressure as patient effort and mayconsequently initiate inspiration by delivering respiratory gases.

Alternatively, the ventilator may detect a flow-triggered event.Specifically, the ventilator may monitor the circuit flow, as describedabove. If the ventilator detects a slight drop in flow duringexhalation, this may indicate, again, that the patient is attempting toinspire. In this case, the ventilator is detecting a drop in bias flow(or baseline flow) attributable to a slight redirection of gases intothe patient's lungs (in response to a slightly negative pressuregradient as discussed above). Bias flow refers to a constant flowexisting in the circuit during exhalation that enables the ventilator todetect expiratory flow changes and patient triggering. For example,while gases are generally flowing out of the patient's lungs duringexhalation, a drop in flow may occur as some gas is redirected and flowsinto the lungs in response to the slightly negative pressure gradientbetween the patient's lungs and the body's surface. Thus, when theventilator detects a slight drop in flow below the bias flow by apredetermined threshold amount (e.g., 2 L/min below bias flow), it mayinterpret the drop as a patient trigger and may consequently initiateinspiration by delivering respiratory gases.

The predetermined exercise period begins at the start of spontaneousventilation. In some embodiments the predetermined exercise period isdetermined by the ventilator. In other embodiments, the predeterminedexercise period is selected or input by a clinician. In someembodiments, the predetermined exercise period is about 1 minute, 2minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8minutes, 9 minutes, or 10 minutes. However, the predetermined exercisetime may be any suitable time frame for providing the patent with anopportunity to spontaneously trigger a breath to provide the diaphragmof the patient with some exercise. However, the exercise period shouldnot be so long that the exercise period deprives a non-triggeringpatient of necessary ventilation.

As discussed above, in some embodiments, the ventilator 100 includes anoxygen module 164. In some embodiments, the oxygen module 164automatically increases a fractionally inspired oxygen (FiO₂) and/orpositive end expiratory pressure (PEEP) delivered to the patient duringthe exercise period. In other embodiments, the oxygen module monitorsSpO₂ during the exercise period. If the oxygen module 164 determines adrop in SpO₂ during the exercise period, the oxygen module 164determines that the pneumatic system 102 of the ventilator 100 needs todeliver more oxygen to the patient. If the oxygen module 164 determinesthat SpO₂ does not drop during the exercise period, then the oxygenmodule 164 does not send any instructions to the pneumatic system 102 ofthe ventilator 100. No instructions are sent to the pneumatic system 102of the ventilator 100 by the oxygen module 164 because the currentoxygen level delivered to the patient 150 is sufficient for ventilatingthe patient 150. In some embodiments, the oxygen module 164 increasesthe level of FiO₂ delivered to the patient by about 5%.

The notification module 115 may further display a notification relatingto the mandatory mode time period, exercise period, detected triggers,oxygen threshold, mode of ventilation, breath type, detected fatigue,monitored FiO₂, monitored SpO₂, monitored PEEP, and/or any otherparameter relating to the exercise of the diaphragm. For example, thenotification may display that the mandatory mode time period is active,that that the exercise period is being utilized, and/or a change to thedelivered oxygen. These notifications may include any of the featuresdiscussed above for a notification message, such as a hierarchicalstructure, display on a remote monitoring system, and/or a summarizeformat with recommendations offered upon selection.

In some embodiments, if the event that occurred is detected fatigue, thefatigue module 117 of the ventilator 100 confirms the detection ofpatient fatigue by the changing back to the previously utilizedmandatory mode of ventilation. In this embodiment, the fatigue module117 after a predetermined rest time that begins when the exercise module160 changes from the spontaneous mode back to the previously utilizedmandatory mode because patient fatigue was detected. In someembodiments, the predetermined rest time is several minutes to a fewhours. For example, the predetermined rest time is about 30 minutes, 45minutes, 1 hour, 1.25 hours, 1.5 hours, 1.75 hours, 2 hours, 3 hours, 4hours, or 5 hours. However, any suitable amount of time to provide thepatient with rest to mitigate and confirm fatigue may be utilized by theventilator 100. The mandatory mode of ventilation provides the patientwith additional ventilation support and thereby is allowing the patientto rest during the predetermined rest time.

In some embodiments, the fatigue module 117 compares the restedparameters to the breached parameters. The fatigue module 117 determinesif the implemented recommendation mitigated and thereby confirmed thedetermined fatigue based on the comparison of the rested parameters tothe breached parameters. If the fatigue module 117 determines that therested parameters have improved by a predetermined amount from thebreached parameters, then the fatigue module 117 determines that theimplemented recommendation mitigated and thereby confirmed the patientfatigue. However, if the fatigue module 117 determines that the restedparameters have not improved by a predetermined amount from the breachedparameters, then the fatigue module 117 determines that the implementedrecommendation did not mitigate the patient fatigue and that the causefor the change in the patient may not have been related to fatigue Insome embodiments, the rested parameter is considered to be improved ifthe rested parameter improved by 75% or more when compared to thebreached parameters.

In other embodiments, the fatigue module 117 compares the restedparameters to the baseline. The fatigue module 117 determines if themandatory mode of ventilation mitigated and thereby confirmed thedetermined fatigue based on the comparison of the rested parameters tothe baseline. If the fatigue module 117 determines that the restedparameters have improved by a predetermined amount when compared to thebaseline, then the fatigue module 117 determines that the implementedrecommendation mitigated and thereby confirmed the patient fatigue.However, if the fatigue module 117 determines that the rested parametershave not improved by a predetermined amount when compared to thebaseline, then the fatigue module 117 determines that the implementedrecommendation did not mitigate the patient fatigue and that the causefor the change in the patient may not have been related to fatigue.

As discussed above, in some embodiments, the rested parameter isconsidered to be improved if the rested parameter improved by 50% ormore when compared to the baseline. In some embodiments, the restedparameter is considered to be improved if the rested parameter improvedby 80% or more when compared to the baseline. In other embodiments, therested parameter is considered to be improved if the rested parameter nolonger breaches the predetermined threshold for determining patientfatigue when compared to the baseline.

If the mandatory mode mitigated the fatigue of the patient, then thepatient is confirmed to have been fatigued. Accordingly, as discussedabove, in some embodiments, if the fatigue module 117 determines thatthe mandatory mode mitigated the fatigue, then the fatigue module 117instructs the notification module 115 to display a notification relatingto the mitigated fatigue.

If the mandatory mode of ventilation did not mitigate the fatigue, thenthe patient may not have been fatigued, the implemented recommendationmay not have been sufficient to mitigate the patient fatigue, and/or thepatient's event may have deteriorated. Accordingly, in some embodiments,if the fatigue module 117 determines that the implemented recommendationdid not mitigate the fatigue, then the fatigue module 117 instructs thenotification module 115 to display a notification relating to theunmitigated fatigue.

As discussed above, the notification module 115 displays notificationrelating to the unmitigated fatigue based on the instructions from thefatigue module 117. The notification includes a notification that thefatigue was not fixed by the implemented recommendation. Thenotification may further include a notice that the patient fatigue wasan incorrect assessment, that the implemented recommendation wasinsufficient to mitigate the patient fatigue, and/or that the patient'scondition may have deteriorated.

FIG. 2 illustrates an embodiment of a method 200 for ventilating apatient with a ventilator that detects patient fatigue. Currentventilators do not monitor, measure, and/or estimate the fatigue of apatient. Patient fatigue could result in longer ventilation times andworsening of the patient's condition. Accordingly, method 200 detectspatient fatigue. In further embodiments, the method 200 displays afatigue notification. In additional embodiments, method 200automatically implements changes to the patient's ventilation tomitigate patient fatigue.

As illustrated, method 200 is performed after the start of ventilation202. The ventilator ventilates the patient based on selected/inputparameters, such as breath type, height, and/or weight. Once ventilationhas begun 202, the ventilation performs a monitoring operation 204.

Method 200 includes a monitoring operation 204. During the monitoringoperation 204, the ventilator monitors one or more parameters. In someembodiments, the parameters are fatigue indicators. In some embodiments,the parameters include inspiratory lung flow, net lung flow, airwaypressure, PaCO₂, VCO₂, E_(di), P_(di), P_(i), cardiac output, V_(t),diaphragm movement, P_(esoph), E_(phr), SPO₂, MV, and etc. Themonitoring operation 204 may be performed by sensors and dataacquisition subsystems. The sensors may include any suitable sensingdevice as known by a person of skill in the art for a ventilator. Insome embodiments, the sensors are located in the pneumatic system, thebreathing circuit, and/or on the patient. In some embodiments, theventilator during the monitoring operation 204 monitors the parametersevery computational cycle (e.g., 2 milliseconds, 5 milliseconds, 10milliseconds, etc.). In other embodiments, the ventilator during themonitoring operation 204 monitors the parameters after a predeterminednumber of breaths (e.g., 1 breath, 2 breaths, 3 breaths, etc.). In otherembodiments, the ventilator during the monitoring operation 204 monitorsthe parameters after a predetermined set sensor time period (e.g., 1second, 2 seconds, 30 seconds, 1 minute, 5 minutes, etc.).

Further, during the monitoring operation 204, the ventilator may derive(which includes estimate) a fatigue indicator based on the sensormeasurements or output. For example, the ventilator during monitoringoperation 204 determines a patient WOB based on sensor output. In someembodiments, the work of breathing is calculated by entering the sensoroutput into the Equation of Motion. In other embodiments, the WOB ofbreathing is derived by inputting various measurements (also known assensor output) from various sensors into breathing algorithms. In someembodiments, the sensor output is monitored inspiratory flow and/or netflow. In other embodiments, at least one of resistance, elastance,and/or compliance estimates derived from the sensor output is utilizedto determine the WOB of the patient. However, any known systems ormethods for calculating a WOB of the patient from sensor output may beutilized. For example, methods exist that calculate work of breathingfrom sensors attached to the body to detect neural or muscular activityas well as methods that determine a work of breathing based onrespiratory flow, respiratory pressure or a combination of both flow andpressure. For example, in one embodiment, the WOB of the patient iscalculated with the following equation: WOB=∫Pressure×Volume.

Other fatigue indicators may need to be derived (which includesestimated) from the monitored parameters. Accordingly, the ventilatorduring monitoring operation 204 may further derive either fatigueindicators, such as RSBI, respiration rate, P_(tid), and etc. In someembodiments, the monitored parameters are directly utilized as fatigueindicators. For example, T_(I) and E_(di) may be directly monitored bythe ventilator during monitoring operation 204.

As illustrated, method 200 includes an establishing a baseline operation205. During the establishing a baseline operation 205, the ventilatorestablishes a baseline for one or more fatigue indicators. The baselinedesignates a normal level or desired level of the fatigue indicator forthe patient. The fatigue indicator is any suitable parameter forproviding an indication of patient fatigue. For example, at least one ofthe following parameters may be utilized as the fatigue indicator:PaCO₂, WOB, VCO₂, EMG of a respiration accessory muscle, E_(di),P_(0.1), diaphragmatic position, P_(di), P_(di,max), P_(i,max), cardiacoutput, velocity of muscle shortening, V_(t), diaphragm movement,P_(esoph), P_(di) maximal relaxation rate, P_(mus) maximum relationrate, abdominal and/or rib cage muscle contractions, paradoxicalbreathing, V_(e alv), respiration rate, (BIS LOS), RSBI, V_(t)/T_(i),P_(di)/P_(di max), T_(i)/T_(tot), V_(d)/V_(t), P_(tid) or(P_(di)/P_(di max))/(T_(i)/T_(tot)), T_(i)/T_(tot)/P_(di)/P_(dimax),respiration muscle pressure divided EMG integral, E_(phr), SpO₂, MV,and/or P_(mus). This list exemplary only and is not meant to limit thedisclosure. In an alternative embodiment, the fatigue indicator is afatigue metric. The fatigue metric is any suitable function of two ormore fatigue indicators. For example, the fatigue metric may add,subtract, divide, and/or multiply two or more fatigue indicators. Thefatigue metric may be any suitable mathematical relationship between twoor more fatigue indicators for determining patient fatigue.

In some embodiments, the ventilator during the establishing a baselineoperation 205 determines a baseline for a fatigue indicator based oninput from a clinician. For example, the clinician may enter the desiredbaseline for the patient. This allows the clinician determine thedesired baseline for a fatigue indicator. The clinician may take intoaccount the patient's history, disease state, sex, and other factorswhen determining the baseline for a fatigue indicator for a patient.

In an alternative embodiment, the ventilator during the establishing abaseline operation 205 determines a baseline for fatigue indicators byaveraging sensor output for each of the fatigued indicators for apredetermined amount of time. The ventilator during the establishing abaseline operation 205 adds the set of measurements or sensor outputgenerated by the repeated sensor measurements for the predeterminedamount of time and then divides the total by the number of measurementstaken for determine the baseline. The predetermined time period may beany suitable amount of time to determining a normal or baselineparameter value for the patient 150. In some embodiments, thepredetermined amount of time is 10 minutes, 30 minutes, 45 minutes, 1hour, 1.5 hours, 2 hours, 6 hours, 12 hours, or 24 hours.

In further, embodiments, some fatigue parameters only exist in a finitenumber of states. Accordingly, for these fatigue indicators apredetermined state will be the baseline. These baselines may bepredetermined and automatically configured on the ventilator. Forexample, absence of paradoxical breathing may be a baseline.Accordingly, the presence of paradoxical breathing is a detected changefrom this baseline.

In some embodiment, the predetermined amount of time starts during theestablishing a baseline operation 205 after the ventilator delivers apredetermined number of breaths (e.g., 1 breath, 2 breaths, 3 breaths, 5breaths, etc.) from the start of ventilation. In other embodiments, thepredetermined amount of time begins after a set start time, such as 1minute after the beginning of ventilation, 5 minutes after the beginningof ventilation, 10 minutes after the beginning of ventilation, 1 hourafter the beginning of ventilation, or 3 hours after the beginning ofventilation.

For example, in some implementations, the following may be utilized asbaselines for the following fatigue indicators:

PaCO₂ is 38-42 mmHg;

PaCO₂ for patients with COPD 42-62 mmHg;

pH of 7.38-7.42;

VCO₂ of 180-200 mL/min;

VCO₂ of 2.5-3.5 mL/Kg/min;

P_(0.1) of 1-2 cmH₂O;

P_(di,max) is about 80 cmH₂O;

P_(i,max) is about 80 cmH₂O;

V_(t) is 5-6 mL/kg;

P_(esoph) is 3-5 cmH₂O;

no paradoxical breathing;

respiration rate is 12-16/min for adults;

RSBI is less than 40;

P_(di)/P_(di max) is around 5-10%;

T_(i)/T_(tot) is about 30%; and

V_(d)/V_(t) is 0.2-0.3.

Further, method 200 includes a change decision operation 206. Theventilator during the change decision operation 206 determines a changefrom the baseline based on the monitored fatigue indicators. A change isdetermined by the ventilator during change decision operation 206 whenthe current sensor output or monitor fatigue parameter is not equivalentor substantially equivalent to the baseline. In some embodiments, afatigue parameter is considered substantially equivalent to the baselinewhen the difference between the fatigue parameter and the baseline isless than 1%. In other embodiments, a fatigue parameter is consideredsubstantially equivalent to the baseline when the difference between thefatigue parameter and the baseline is less than 3%. In furtherembodiments, a fatigue parameter is considered substantially equivalentto the baseline when the difference between the fatigue parameter andthe baseline is less than 5%.

Next, method 200 includes a fatigue comparing operation 207. Theventilator during the fatigue comparing operation 207 compares adetected change to a fatigue threshold. The fatigue threshold is anysuitable fatigue indicator threshold for providing an indication ofpatient fatigue. In embodiments, the fatigue indicator threshold is athreshold for a fatigue metric. In some embodiments, the fatigueindicator threshold is a detected rate of change in a fatigue indicatorand/or metric. In some embodiments, the fatigue threshold is at leastone of the following thresholds:

work of breathing decrease below the baseline;

work of breathing increases above the baseline followed by a decreasebelow the baseline;

PaCO₂ increases from the baseline;

VCO₂ decreases from the baseline;

EMG of an accessory muscle indicates use of the accessory muscle;

E_(di) decreases from the baseline;

P_(0.1) increases and then decreases from the baseline;

diaphragmatic position becomes flattened;

P_(di) decreases from the baseline;

P_(di,max) decreases from the baseline;

P_(i,max) decreases from the baseline;

cardiac output does not increase from the baseline with an increasingload,

velocity of muscle shortening decreases from the baseline;

EMG time domain decreases from the baseline;

EMG, frequency domain decreases from the baseline;

V_(t) decreases from the baseline;

diaphragm movement imaging shows reduced movement from the baseline;

P_(esoph) decreases from the baseline;

P_(di) Maximum Relaxation Rate decreases from the baseline;

P_(mus) Maximum Relaxation Rate decreases from the baseline;

alternating abdominal/rib cage muscle contractions occur or increase infrequency from the baseline;

V_(e alv) decreases from the baseline;

respiration rate increases followed by a decrease from the baseline;

BIS LOS is normal;

RSBI increases from the baseline;

V_(t)/T_(i) decreases from the baseline;

P_(di)/P_(di max) increases from the baseline;

T_(i)/T_(tot) increases from the baseline;

V_(d)/V_(t) increases from the baseline;

P_(tid) increases from the baseline;

T_(i)/T_(tot)/P_(di)/P_(dimax) increases from the baseline;

Respiration muscle pressure/EMG integral decreases from the baseline;

E_(di) increases while E_(phr) increases and P_(di) decreases from thebaseline;

P_(di,max) decreases from the baseline;

P_(i,max) decreases from the baseline;

E_(di) increases and at least one of a decrease in V_(t), a decrease inVCO₂, a decrease in SpO₂, an increase in P_(0.1), and a decrease in MVfrom the baseline occurs;

P_(mus) decreases and at least one of a decrease in V_(t), a decrease inVCO₂, a decrease in SpO₂, and a decrease in MV from the baseline occurs;

PaCO₂ increases from the baseline by at least 10 mmHg,

VCO₂ decrease from the baseline by more than 20%,

E_(di) decreases from the baseline by at least 25%,

E_(di) stays the same while the velocity of muscle shortening decreasesfrom the baseline;

P_(0.1) increases above 4 cm of H₂O and then decreases by at least 2 cmof H₂O,

P_(di) decreases by at least 10% from the baseline;

P_(di,max) decreases by at least 20% from the baseline;

P_(i,max) decreases by at least 20% from the baseline;

velocity of muscle shortening decreases by at least 25% from thebaseline;

EMG time domain is less than 50 uV;

EMG, frequency domain decreases by more than 20% from the baseline;

V_(t) is below 4 mL/kg;

P_(esoph) decreases by at least 10% from the baseline;

P_(di) Maximum Relaxation Rate decreases by at least 20% from thebaseline;

P_(mus) Maximum Relaxation Rate decreases by at least 20% from thebaseline;

presence of paradoxical breathing;

V_(e alv) decreases by at least 20% from the baseline;

respiration rate increases above 35 breaths a minute;

respiration rate increases by at least 25% from the baseline followed bya decrease;

RSBI increases above 105;

V_(t)/T_(i) decreases by 30% from the baseline;

P_(di)/P_(di max) is above 40% from the baseline;

T_(i)/T_(tot) is greater than 40% from the baseline;

V_(d)/V_(t) increases by 20% from the baseline;

V_(d)/V_(t) is greater than 40% from the baseline;

P_(tid) increases above 0.15; and

T_(i)/T_(tot)/P_(di)/P_(dimax) is greater than 40% from the baseline.

This list exemplary only and is not meant to limit the disclosure. Anysuitable thresholds for determining fatigue in a patient duringventilation may be utilized by the ventilator.

Method 200 also includes a fatigue determining operation 208. Theventilator during the fatigue determining operation 208 determines if adetected change breaches a fatigue threshold. If the ventilator duringthe fatigue determining operation 208 determines that one or moredetected changes breach their corresponding fatigue thresholds, theventilator determines that the patient is fatigued 210. If theventilator during the fatigue determining operation 208 determines thatone or more detected changes do not breach the fatigue threshold, theventilator determines that the patient is not fatigued and continues toperform monitoring operation 204.

In some embodiments, the ventilator during the fatigue determiningoperation 208 monitors numerous fatigue indicators to determine if anychanges of the fatigue indicators breach their corresponding fatiguethresholds. In alternative embodiments, the ventilator during thefatigue determining operation 208 monitors numerous fatigue indicatorsto determine if a predetermined number or a select group of the fatigueindicators have changed to breach their corresponding fatigue threshold.In other embodiments, the ventilator during the fatigue determiningoperation 208 monitors only one predetermined fatigue indicator todetermine if a change in that predetermined fatigue indicator breachesthe corresponding fatigue threshold.

In additional embodiments, the ventilator during the fatigue comparingoperation 207 and/or fatigue determining operation 208 may determine thelevel of fatigue detected. To determine the level of fatigue detected,the ventilator during the fatigue comparing operation 207 and/or fatiguedetermining operation 208 may weigh how much how much a fatiguethreshold was breached, by how many fatigue thresholds were breached,and/or a rate at which any breach is increasing. The ventilator duringthe fatigue comparing operation 207 and/or fatigue determining operation208 may utilize a mathematical algorithm for weighing the aboveparameters to determine the level of fatigue detected. In someembodiments, the ventilator determines the patient fatigue as high,medium, or low. In other embodiments, a fatigue index is determined bythe ventilator during the fatigue comparing operation 207 and/or fatiguedetermining operation 208. The fatigue index may indicate the level offatigue experienced by the patient. For example, the fatigue index maybe a scale of 1-10 or 1-3. The higher the degree of patient fatigue, thehigher the fatigue index listed by the ventilator (1 may be the high endor 10 and 3 may be the high end of the scale depending upon the desiredindex). The listed fatigue index is above are not meant to be limiting.Any suitable indication of a patient's fatigue level may be utilized bythe ventilator during the fatigue comparing operation 207 and/or fatiguedetermining operation 208 as the fatigue index, including symbols,colors (i.e., red, yellow, and green to designate different fatiguelevels), text, numbers, and/or animations.

In some embodiments, method 200 includes a displaying operation 212 asillustrated in FIG. 3A. FIG. 3A illustrates an embodiment of a methodfor notifying a clinician of patient fatigue during ventilation. Duringdisplaying operation 212, the ventilator after patient fatigue isdetected 210, displays a fatigue notification message. The ventilatorduring displaying operation 212 determines an appropriate notificationbased on the fatigue comparing operation 207 and/or fatigue determiningoperation 208. When patient fatigue is implicated, many clinicians maynot be aware of adjustments to parameters that may reduce or eliminatefatigue. As such, upon detection of patient fatigue, the ventilatorduring displaying operation 212 may notify the clinician that patientfatigue is implicated and/or provide recommendations to the clinicianfor mitigating patient fatigue. Accordingly, the notification messagemay include a recommendation for mitigating patient fatigue. Forexample, ventilator during displaying operation 212 may notify theclinician by displaying a notification on a display and/or within awindow of the GUI. According to additional embodiments, the notificationis communicated to and/or displayed on a remote monitoring system.According to alternative embodiments, the notification is any audioand/or visual notification.

In order to accomplish the various aspects of the notification messagedisplay, the ventilator during displaying operation 212 may communicatewith various ventilator components or modules. That is, the ventilatorduring displaying operation 212 may receive an indication that thepatient is fatigued by any suitable means. In addition, the ventilatorduring displaying operation 212 may receive information regarding one ormore parameters that implicated the presence of patient fatigue andinformation regarding the patient's ventilator settings and treatment.Further, according to some embodiments, the ventilator during displayingoperation 212 may have access to a patient's diagnostic information(e.g., regarding whether the patient has ARDS, COPD, asthma, emphysema,or any other disease, disorder, or condition).

In some embodiments, notifications determined by ventilator duringdisplaying operation 212 may be provided according to a hierarchicalstructure such that a notification may be initially presented insummarized form and, upon clinician selection, an additional detailednotification may be displayed. According to alternative embodiments, anotification determined by ventilator during displaying operation 212 isinitially presented without a recommendation and, upon clinicianselection, a recommendation message is displayed. Alternatively oradditionally, the notification determined by ventilator duringdisplaying operation 212 simultaneously displays a detection of patientfatigue with a recommendation message in any suitable format orconfiguration.

Specifically, according to some embodiments, the notification alerts theclinician as to the detection of a fatigue, a change in a patient'sfatigue, or an effectiveness of ventilator treatment of patient fatigue.For example, the notification message determined by ventilator duringdisplaying operation 212 may alert the clinician that fatigue has beendetected and the parameters that indicated the patient fatigue (i.e.,WOB, RSBI, V_(t), E_(di), and etc.). The notification may further alertthe clinician regarding the particular breach or level of breach of theparticulars parameter(s) that implicated patient fatigue (e.g., WOB,cardiac output, P_(di), VCO₂, etc.) For example, the notification mayrecite that patient fatigue is detected and then list the WOBmeasurements that indicated the patient fatigue.

In some embodiments, the notification recites the following messages:

fatigue detected;

fatigue warning;

fatigue implicated; and

fatigue notification.

In some embodiments, the notification may further recite the one or morefatigue indicator measurements that indicated the patient fatigue. Inother embodiments, the notification may also recite the one or morefatigue thresholds.

In other embodiments, the level of fatigue is displayed in thenotification by the ventilator during displaying operation 212. Forexample, the notification may list that a high, medium, or low level ofpatient fatigue is detected. In other embodiments, a fatigue index maybe listed in the notification. As discussed above the fatigue index mayindicate the level of patent fatigue as determined by ventilator.

Additionally, according to embodiments as discussed above, thenotification may provide various suggestions to the clinician foraddressing detected patient fatigue. According to additionalembodiments, the notification may be based on the particularparameter(s) that implicated the patient fatigue. Additionally oralternatively, the recommendation may be based on current ventilatorsettings (e.g., breath type). Additionally or alternatively, therecommendation may be based on a diagnosis and/or other patientattributes. Further still, the recommendation may include a primaryrecommendation message and a secondary recommendation message. Forexample, the primary recommendation message may recite, “considerswitching breath types” and the secondary recommendation message mayrecite, “consider switching to VC+ breath type.” In another example, theprimary recommendation message may recite, “consider utilizing a basallevel of pressure support in the PA breath” and the secondaryrecommendation may recite, “consider utilizing 5 cm H₂O as your basallevel of support.”

The ventilator during displaying operation 212 may generate anotification via any suitable method or system. For example, thenotification may be provided as a tab, banner, dialog box, or othersimilar type of display. Further, the notification may be provided alonga border of the graphical user interface, near an alarm display or bar,or in any other suitable location. A shape and size of the notificationmay further be optimized for easy viewing with minimal interference toother ventilator displays. The notification message may be furtherconfigured with a combination of icons and text such that the clinicianmay readily identify the message as a notification message.

The ventilator during displaying operation 212 may generate one or morerecommendations via any suitable systems or methods. The one or morerecommendations may provide suggestions and information regardingaddressing the detected patient fatigue. In some embodiments, the one ormore recommendations identifies the parameters that implicated thedetected condition, provides suggestions for adjusting the one or moreparameters to address the detected fatigue, provides suggestions forchecking ventilator equipment or patient position, and/or provides otherhelpful information. For example, if fatigue is implicated, thenotification may include one or more of the following recommendations:

consider switching to invasive ventilation;

consider switching to a negative feedback breath type;

consider switching to a PS, PC, VC, or VS breath type;

consider increasing ventilation support;

consider increasing support setting in the PA breath type;

consider increasing support setting in the DEA breath type;

consider increasing support setting in a positive feedback breath type;

consider increasing set respiratory rate;

consider utilizing a basal level of support in the PA breath type;

consider utilizing a basal level of support in the DEA breath type; and

consider utilizing a basal level of support in a positive feedbackbreath type.

This list of recommendations is exemplary only. Any suitablerecommendation for increasing the ventilator support of the patient maybe utilized as a recommendation to mitigate patient fatigue.

As discussed above, in some embodiments, after patient fatigue isdetected by the ventilator during the fatigue determining operation 208,the ventilator during displaying operation 212 recommends switching fromnon-invasive ventilation to invasive ventilation. Studies have shownthat waiting too long before switching from a non-invasive ventilationto invasive ventilation when a patient is responding poorly toventilation (e.g., detecting patient fatigue) has been linked to anincreased mortality rate. Accordingly, if patient fatigue is detected byventilator during the fatigue determining operation 208, the ventilatorduring displaying operation 212 may recommend switching fromnon-invasive ventilation (i.e., using a nasal mask and other settings)to invasive ventilation (i.e., using an endotracheal tube and othersettings).

In some embodiments when a positive feedback breath type is beingutilized by the ventilator, method 200 includes a modifying breath typeoperation 214 as illustrated in FIG. 3B. FIG. 3B illustrates anembodiment of a method for managing patient fatigue during ventilation.In some embodiments, during the modifying breath type operation 214, theventilator after patient fatigue is detected 210 modifies the positivefeedback breath type by increasing the support setting, which increasesthe level of pressure support provided by the positive feedback breathtype. In other embodiments, during the modifying breath type operation214, the ventilator after patient fatigue is detected 210 modifies thepositive feedback breath type to provide a basal level of pressuresupport. With positive feedback algorithms, the amount of supportprovided by the ventilator is proportional to the monitored patient'swork of breathing. However, if a patient becomes fatigued, the patientmay decrease their work of breathing. In positive feedback breath types,support is withdrawn as the patient decreases his or her work ofbreathing. Therefore, the patient receives less support as the patientbecome more fatigued, which may cause the patient's fatigue to worsen.Accordingly, the basal level of pressure support is a set pressure,pressure level, or support setting that provides the minimum amount ofpressure support that the positive feedback breath type deliversregardless of the patient derived WOB. Accordingly, the basal level ofpressure support limits the positive feedback from reducing supportbeyond a predetermined threshold. Therefore, the patient receives thisminimal amount of pressure support in an attempt to mitigate thedetected patient fatigue. In one embodiment, the positive feedbackbreath type is a PA breath type. In another embodiment, the positivefeedback breath type is a DEA breath type. In some embodiments, theventilator performs the modifying breath type operation 214 and thedisplaying operation 212 concurrently.

In some embodiments when a positive feedback breath type is beingutilized by the ventilator, method 200 includes a changing breath typeoperation 216 as illustrated in FIG. 3C. FIG. 3C illustrates anembodiment of a method for managing patient fatigue during ventilation.During the changing breath type operation 216, the ventilator afterpatient fatigue is detected 210, switches from the positive feedbackbreath type to a non-positive feedback breath type. For example, theventilator during the changing breath type operation 216 may switch to anegative feedback breath type (e.g., VS or VC+) or to another breathtype (e.g., VC, VS, and PC). The change in breath type prevents afatigued patient from receiving less support with each increasing degreeof fatigue. In some embodiments, the ventilator performs the changingbreath type operation 216 and the displaying operation 212 concurrently.

In additional embodiments, method 200 includes a confirming operation218. The confirming operation 218 may be performed by the ventilatorafter the ventilator performs the modifying breath type operation 214 orthe changing breath type operation 216 as illustrated in FIGS. 3B and3C. The confirming operation 218 determines if the detected patientfatigue 210 was mitigated by performance of the modifying breath typeoperation 214 or the changing breath type operation 216. The confirmingoperation 218 includes a rest time determining operation 220, a restmonitoring operation 224, a rest comparing operation 226, and animprovement determining operation 228 as illustrated in FIG. 4. FIG. 4illustrates an embodiment of a method for determining if an implementedrecommendation mitigated patient fatigue. Accordingly, as discussed withreference to confirming operation 218, referring to implementing arecommendation refers to the modifying breath type operation 214 and/orthe changing breath type operation 216.

The ventilator during the rest time determining operation 220 determinesif a predetermined rest time has expired. In some embodiments, thepredetermined rest time is selected by the operator. In otherembodiments, the predetermined rest time is determined by theventilator. The implemented recommendation, such as the modified breathtype or the changed breath type, provides the patient with additionalventilation support and thereby allows the patient to rest during thepredetermined rest time. Accordingly, the predetermined rest time beginswhen the recommendation is implemented. If the ventilator during therest time determining operation 220 determines that the predeterminedrest time has expired, the ventilator selects to perform rest monitoringoperation 224. If the ventilator during the rest time determiningoperation 220 determines that the predetermined rest time has notexpired, the ventilator selects to re-perform the rest time determiningoperation 220. In some embodiments, when the ventilator during the resttime determining operation 220 determines that the predetermined resttime has expired, the ventilator selects to perform a return settingoperation 222 prior to performing the rest monitoring operation 224.

The ventilator during the return setting operation 222 changes theventilator settings back to the ventilator settings that were utilizedto ventilate the patient during the fatigue detection. For example, ifthe patient is currently being ventilated with a negative feedbackbreath type, but was being ventilated with a positive feedback breathtype during the detection of the fatigue, the ventilator during thereturn setting operation 222 switches the breath type back to thepreviously utilized positive feedback breath type and associatedsettings. The settings are returned to the settings utilized duringfatigue detection to ensure that any difference between the restedparameters and the baseline cannot be attributed to the differentventilator settings utilized during ventilation of the patient at thetime of measurement.

The ventilator during the rest monitoring operation 224 monitors forrested parameters. As discussed above, rested parameters are the one ormore fatigue indicators of the patient determined after thepredetermined rest time. The rest monitoring operation 224 is similar tothe monitoring operation 204 described above other than rest monitoringoperation 224 is performed specifically after the predetermined resttime expires. Accordingly, the above description of the monitoringoperation 204 applies to the rest monitoring operation 224.

In some embodiments, the ventilator during the rest comparing operation226 compares the rested parameters to the baseline. The ventilatordetermines the rested parameters during the performance of the restmonitoring operation 224. The baseline, as discussed above, designates anormal level or desired level of the fatigue indicator for the patient.In some embodiments, the clinician inputs the baseline. This allows theclinician determine the desired baseline for a fatigue indicator. In analternative embodiment, the ventilator determines a baseline for fatigueindicators by averaging sensor output for each of the fatiguedindicators for a predetermined amount of time. In further, embodiments,some fatigue parameters only exist in a finite number of states.Accordingly, for these fatigue indicators a predetermined state will bethe baseline. These baselines may be predetermined and automaticallyconfigured on the ventilator. For example, absence of paradoxicalbreathing may be a baseline. Accordingly, the presence of paradoxicalbreathing is a detected change from this baseline.

In other embodiments, the ventilator during the rest comparing operation226 compares the rested parameters to the breached parameter. Theventilator determines the rested parameters during the performance ofthe monitoring operation 204. The breached parameters, as discussedabove are the one or more fatigue indicator of the patient that breacheda threshold to indicate the detected patient fatigue 210. Accordingly,ventilator determines the breached parameters during the performance ofthe monitoring operation 204.

Next, the ventilator during the improvement determining operation 228determines if the rested parameters have improved when compared to thebaseline. In some embodiments, the rested parameters are considered tohave improved if the rested parameter improved by 80% or more whencompared to the baseline. In some embodiments, the rested parameters areconsidered to have improved if the rested parameter improved by 95% ormore when compared to the baseline. In other embodiments, the restedparameter is considered to be improved if the rested parameter no longerbreaches the predetermined threshold for determining patient fatiguewhen compared to the baseline. In other embodiments, the restedparameter is considered to be improved if the rested parameter hasimproved so that the rested parameter is within 5% of the baseline. Ifthe ventilator during improvement determining operation 228 determinesthat the rested parameters have improved compared to the baseline, thenthe patient fatigue has been mitigated 230. If the rested parametershave improved, then the implemented recommendation has allowed thepatient to rest and reduced or mitigated the patient's fatigue 230 andconfirmed the fatigue detection by the ventilator. If the ventilatorduring improvement determining operation 228 determines that the restedparameters have not improved compared to the baseline, then thepatient's condition has not been mitigated 232. If the rested parametershave not improved, then the implemented recommendation has either notallowed the patient to rest enough to reduce or mitigate the patient'sdetected fatigue 210, something else besides patient fatigue that mimicsthe symptoms of patient fatigue is affecting the patient, and/or thepatient's condition may have deteriorated.

In some embodiments, the displaying operation 212 is performed after theconfirming step. The ventilator after determining that patient fatigueis mitigated 230, displays a fatigue mitigation notification messageduring displaying operation 212. The ventilator after determining thatthe patient fatigue is unmitigated 232, displays an unmitigated patientcondition notification message during displaying operation 212. Thenotification displayed by the displaying operation 212 is similar to thenotification described above and therefore may exhibit any of thefeatures described above for a notification message, such as ahierarchical structure, display on a remote monitoring system, and/or asummarize format with recommendations offered upon selection.

The notification after the ventilator determined mitigated fatigue 230may include a notification that the fatigue was fixed by the implementedrecommendation. The notification after the ventilator determinedmitigated fatigue 230 may further include a notice that the patientfatigue was the correct assessment, that the implemented recommendationwas sufficient to mitigate the patient fatigue, and/or that thepatient's condition is improved. In some embodiments, the notificationafter the ventilator determined mitigated fatigue 230 may furtherinclude one or more recommendations for ventilating the patient now thatthe patient is no longer fatigued. In further embodiments, thenotification after the ventilator determined mitigated fatigue 230 mayfurther include a reference to the rested parameters, the breachedparameters, and/or the predetermined thresholds of the breachedparameters. For example, the notification after the ventilatordetermined mitigated fatigue 230 may include:

Fatigue mitigated;

Consider switching to a positive feedback breath type;

Patient fatigue confirmed;

Fatigue reduced by at least 95%; and

etc.

The notification after the ventilator determines that the patientfatigue is unmitigated 232 may include a notification that the fatiguewas not fixed by the implemented recommendation. The notification afterthe ventilator determines that the patient fatigue is unmitigated 232may further include a notice that the patient fatigue was an incorrectassessment, that the implemented recommendation was insufficient tomitigate the patient fatigue, and/or that the patient's condition mayhave deteriorated. In some embodiments, the notification after theventilator determines that the patient fatigue is unmitigated 232 mayfurther include one or more recommendations for dealing with theunmitigated fatigue. In further embodiments, the notification after theventilator determines that the patient fatigue is unmitigated 232 mayfurther include a reference to the rested parameters, the breachedparameters, and/or the predetermined thresholds of the breachedparameters. For example, the notification relating to the unmitigatedfatigue may include:

Fatigue treatment failed;

Patient condition deteriorating—Fatigue unmitigated;

Warning patient not responding to fatigue treatment;

Warning patient not fatigued, consider checking other causes of a lowwork of breathing;

Warning fatigue detected in error, consider checking other parameters todetermine the cause of the patient's detected negative condition; and

etc.

In some embodiments, a microprocessor-based ventilator that accesses acomputer-readable medium having computer-executable instructions forperforming the method of ventilating a patient with a ventilator isdisclosed. This method includes repeatedly performing the stepsdisclosed in method 200 above and/or as illustrated in FIGS. 2, 3A, 3B,and/or 3C.

In some embodiments, the ventilator system includes: means formonitoring a plurality of fatigue indicators; means for establishing abaseline for the fatigue indicators; means for determining a change fromthe baseline based on the monitored fatigue indicators; means forcomparing the change to a fatigue threshold; means for detectingrespiratory fatigue based on the step of comparing the change to thefatigue threshold; and means for displaying a fatigue notification afterthe step of detecting respiratory fatigue.

FIG. 5 illustrates an embodiment of a method 500 for ventilating apatient on a ventilator. As discussed above, patients that areventilated for an extended period of time in a mandatory mode ofventilation may develop diaphragmatic weakness or fatigue. The non-useof the diaphragm for the extended period of time during the mandatorymode may lead to diaphragm atrophy causing the diaphragmatic weakness.Accordingly, method 500 exercises the diaphragm of the patient in anattempt to mitigate or prevent the diaphragm atrophy and/or weakness.Method 500 begins after the start of ventilation.

In some embodiments, method 500 is performed or activated based onclinician input. In other embodiments, method 500 is activated after apatient has been ventilated based on a mandatory mode of ventilation fora certain amount of time. The certain amount of mandatory mode time maybe input by the clinician or predetermined by the ventilator.

As illustrated, method 500 includes a mandatory mode operation 502. Theventilator during the mandatory mode operation 502 ventilates a patientbased on a set mandatory mode. In some embodiments, the set mandatorymode is selected or input by an operator. In other embodiments, the setmandatory mode is determined by the ventilator. Several different breathtypes may be utilized during the mandatory mode. For example, a PC, VC,or VC+ breath type may be utilized during the mandatory mode. Asdiscussed above, a mandatory mode of ventilation delivers mandatorybreaths to a patient based on a set respiratory rate. During a mandatorymode of ventilation, the patent cannot influence when inspiration orexhalation occurs.

In some embodiments, method 500 includes a time period determinationoperation 504. The ventilator during time period determination operation504 determines if a time period has expired. The time period begins withthe start of the mandatory mode of ventilation. The start of themandatory mode of ventilation is any time the ventilator is switchedinto a mandatory mode of ventilation from a different mode ofventilation or at the beginning of ventilation just after the ventilatoris turned on. In some embodiments, the time period is about 30 minutes,45 minutes, 60 minutes, 75 minutes, 90 minutes, 105 minutes, or 120minutes. The time period may be any suitable amount of time thatprovides the spontaneous mode often enough to the patient to prevent ormitigate diaphragm atrophy or weakness. The time period may bedetermined by the operator or predetermined by the ventilator. If theventilator determines during the time period determination operation 504that the time period has expired, the ventilator selects to perform aspontaneous mode operation 506. If the ventilator determines during timeperiod determination operation 504 that the time period has not expired,the ventilator selects to continue to perform the time perioddetermination operation 504.

In other embodiments, the ventilator during method 500 switches from themandatory mode to the spontaneous mode after a specific event, such as apredetermined number of breaths, inspirations, or cycles. In furtherembodiments, the ventilator during method 500 switches from themandatory mode to the spontaneous mode based on clinician input orselection.

Further, method 500 includes a spontaneous mode operation 506. Theventilator during the spontaneous mode operation 506 ventilates thepatient based on a spontaneous mode of operation. In some embodiments,the breath type delivered during the spontaneous mode is selected orinput by an operator. In other embodiments, the breath type deliveredduring the spontaneous mode is determined by the ventilator. Severaldifferent breath types may be utilized during the spontaneous mode. Forexample, a CPAP, Bilevel, VS, PS, PA, or TC breath type may be utilizedduring the spontaneous mode. As discussed above, during a spontaneousmode of ventilation, inspiration and/or exhalation is delivered upon thedetection of inspiratory and/or expiratory effort by the patient basedon a trigger type. However, for safety measures, inspiration andexhalation may be delivered after a predetermined amount of time passesto insure that the patient receives breathing gas in the event thepatient stops making inspiratory and/or expiratory patient efforts. Thespontaneous mode operation 506 is performed by the ventilator until thefirst of several events occur, which are determined in an eventdetermination operation 508. Accordingly, the ventilator performs theevent determination operation 508 while performing the spontaneous modeoperation 506. Accordingly, the event determination operation 508 andthe spontaneous mode operation 506 may be performed simultaneously.

Further, in some embodiments, during the spontaneous mode operation 506,the ventilator automatically increases a fractionally inspired oxygen(FiO₂) and/or positive end expiratory pressure (PEEP) delivered to thepatient during the exercise period. Alternatively, during thespontaneous mode operation 506, the ventilator in some embodiments,monitors SpO₂. During this embodiment, the ventilator during thespontaneous mode operation 506 determines if the monitored SpO₂ droppedduring the exercise period. Based on this determination, the ventilatorduring the spontaneous mode operation 506 may increase the amount ofoxygen delivered to the patient.

If the ventilator during the spontaneous mode operation 506 determinesthat the SpO₂ dropped during the exercise period, then the ventilatordelivers more oxygen to the patient. If the ventilator during thespontaneous mode operation 506 determines that the SpO₂ does not dropduring the exercise period, then the ventilator does not change theamount of oxygen delivered to the patient. The ventilator does notchange the amount of oxygen delivered to the patient because the amountof oxygen the patient is receiving is sufficient for ventilating thepatient. In some embodiments, the ventilator 100 during the spontaneousmode operation 506 increases the level of FiO₂ delivered to the by about5%.

As illustrated, method 500 includes an event determination operation508. The ventilator during the event determination operation 508monitors for the occurrence of an event. If ventilator determines thatan event occurred during event determination operation 508, theventilator selects to perform mandatory mode operation 502. Accordingly,the ventilator during the mandatory mode operation 502 delivers thepreviously set mandatory mode of operation to the patient. If theventilator does not determine an occurrence of an event during eventdetermination operation 508, the ventilator selects to continue toperform spontaneous mode operation 506.

The ventilator during the event determination operation 508 monitors foran occurrence of one or more events. As soon as the ventilator duringthe event determination operation 508 determines that one event of aplurality of event occurs, the ventilator selects to perform mandatorymode operation 502. In other words, the ventilator selects to performmandatory mode operation 502 based on the first of any of the pluralityof events to occur.

In some embodiments, the event is the detection of patient fatigue. Thepatient fatigue may be detected by the ventilator based on method 200 asdescribed above. In some embodiments, at least one of the fatigueindicators utilized by method 200 to detect fatigue during method 500 isWOB.

In additional embodiments the event is the detection of a trend towardspatient fatigue. The detection of a trend toward patient fatigue isdetermined by the ventilator when two or more consecutive changes fromthe baseline in a fatigue indicator are detected that do not breach thefatigue threshold but get consecutively closer to breaching the fatiguethreshold.

In other embodiments, the event is the expiration of an exercise period.The predetermined exercise period begins at the start of spontaneousventilation. In some embodiments the predetermined exercise period isdetermined by the ventilator. In other embodiments, the predeterminedexercise period is selected or input by a clinician. In someembodiments, the predetermined exercise period is about 1 minute, 2minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8minutes, 9 minutes, or 10 minutes. However, the predetermined exercisetime may be any suitable time frame for providing the patent with anopportunity to spontaneously trigger a breath to provide the diaphragmof the patient with some exercise. However, the exercise period shouldnot be so long that the exercise period deprives a non-triggeringpatient with necessary ventilation.

In further embodiments, the event is the expiration of an exerciseperiod during which no inspiration triggers are detected. In thisembodiment, if a trigger is detected, the ventilator continues toventilate the patient in the spontaneous mode of ventilation untilpatient fatigue is detected or until no triggers are detected for anentire duration of the set exercise period. In this embodiment, everytime a trigger is detected, the exercise period starts over until atrigger is not detected for the entire exercise period. Accordingly, inthis embodiment, if the patient continues to trigger and does not getfatigued, the patient could be ventilated in the spontaneous mode untilremoved from the ventilator or until a clinician switches the mode ofventilation.

There are several different trigger types or systems and/methodsutilized by the ventilator for detecting patient triggers and/or cycles.In some embodiments, the trigger type for detecting patient effort maybe selected or input by an operator. In some embodiments, the triggertype is automatically selected by the ventilator. Any suitable type oftriggering detection for determining a patient trigger may be utilizedby the ventilator, such as nasal detection, diaphragm detection, and/orbrain signal detection. Further, the ventilator may detect patienttriggering via a pressure-monitoring method, a flow-monitoring method,direct or indirect measurement of neuromuscular signals, or any othersuitable method, which are described in more detail above. Sensorssuitable for this detection may include any suitable sensing device asknown by a person of skill in the art for a ventilator. In addition, thesensitivity of the ventilator to changes in pressure and/or flow may beadjusted such that the ventilator may properly detect the patienteffort, i.e., the lower the pressure or flow change setting the moresensitive the ventilator may be to patient triggering.

In some embodiments, method 500 includes a displaying operation. Theventilator during the displaying operation displays one or morenotifications relating to the time period, exercise period, detectedtriggers, oxygen threshold, mode of ventilation, breath type, detectedfatigue, monitored FiO₂, monitored PEEP, and/or any other parameterrelating to the exercise of the diaphragm. For example, the notificationmay display that the time period is active, that the exercise period isbeing utilized, and/or a change to the delivered oxygen. Thesenotifications include any of the features discussed above for anotification message, such as a hierarchical structure, display on aremote monitoring system, and/or a summarize format with recommendationsoffered upon selection.

For example, the ventilator during displaying operation may notify theclinician by displaying a notification on a display and/or within awindow of the GUI. According to additional embodiments, the notificationis communicated to and/or displayed on a remote monitoring system.According to alternative embodiments, the notification is any audioand/or visual notification.

In additional embodiments, if the event determination operation 508detects patient fatigue, method 500 further confirms the detectedfatigue. The confirming operation performed by method 500 is identicalto confirming operation 218 as illustrated in FIG. 3C and FIG. 4 and asdescribed above. However, the changing breath type operation 216 isspecific to changing from a spontaneous mode breath type delivered bythe ventilator during the spontaneous mode operation 506 to a mandatorymode breath type utilized in the set mandatory mode as was previouslyutilized by the ventilation during mandatory mode operation 502 ofmethod 500.

In some embodiments, the displaying operation of method 500 is performedafter the confirming step. The ventilator after determining that patientfatigue is mitigated, displays a fatigue mitigation notification messageas described above for method 200 and as illustrated in FIG. 3C. Theventilator after determining that the patient fatigue is unmitigated,displays an unmitigated patient event notification message as describedabove for method 200 and as illustrated in FIG. 3C. The notificationdisplayed by the displaying operation 212 is similar to the notificationdescribed above and therefore may exhibit any of the features describedabove for a notification message, such as a hierarchical structure,display on a remote monitoring system, and/or a summarize format withrecommendations offered upon selection.

In some embodiments, a patient's diaphragm may develop weakness duringan assist/control mode, because the ventilator may still be performingthe bulk of the work for the patient during ventilation. Accordingly,method 500 may be performed according to the disclosure listed aboveexcept that the mandatory mode of ventilator is replaced with theassist/control mode of ventilation.

In some embodiments, a microprocessor-based ventilator that accesses acomputer-readable medium having computer-executable instructions forperforming the method of ventilating a patient with a ventilator isdisclosed. This method includes repeatedly performing the stepsdisclosed in method 500 above and/or as illustrated in FIG. 5

In some embodiments, the ventilator system includes: means forventilating a patient based on a set mandatory mode of ventilation;means for switching from the mandatory mode of ventilation to thespontaneous mode of ventilation to ventilate the patient until the firstof the following events occur: 1) detection of patient fatigue, and 2)no inspiratory triggers are detected and expiration of a predeterminedexercise period; and upon occurrence of the event, means for ventilatingthe patient based on the set mandatory mode of ventilation.

In some embodiments, the ventilator system includes: means forventilating a patient based on a set mandatory mode of ventilation;means for switching from the mandatory mode of ventilation to thespontaneous mode of ventilation to ventilate the patient until the firstof the following events occur: 1) detection of patient fatigue, and 2)expiration of a predetermined exercise period; and upon occurrence ofthe event, means for ventilating the patient based on the set mandatorymode of ventilation.

Those skilled in the art will recognize that the methods and systems ofthe present disclosure may be implemented in many manners and as suchare not to be limited by the foregoing exemplary embodiments andexamples. In other words, functional elements being performed by asingle or multiple components, in various combinations of hardware andsoftware or firmware, and individual functions, can be distributed amongsoftware applications at either the client or server level or both. Inthis regard, any number of the features of the different embodimentsdescribed herein may be combined into single or multiple embodiments,and alternate embodiments having fewer than or more than all of thefeatures herein described are possible. Functionality may also be, inwhole or in part, distributed among multiple components, in manners nowknown or to become known. Thus, myriad software/hardware/firmwarecombinations are possible in achieving the functions, features,interfaces and preferences described herein. Moreover, the scope of thepresent disclosure covers conventionally known manners for carrying outthe described features and functions and interfaces, and thosevariations and modifications that may be made to the hardware orsoftware firmware components described herein as would be understood bythose skilled in the art now and hereafter.

Numerous other changes may be made which will readily suggest themselvesto those skilled in the art and which are encompassed in the spirit ofthe disclosure and as defined in the appended claims. While variousembodiments have been described for purposes of this disclosure, variouschanges and modifications may be made which are well within the scope ofthe present invention. Numerous other changes may be made which willreadily suggest themselves to those skilled in the art and which areencompassed in the spirit of the disclosure and as defined in theappended claims.

What is claimed is:
 1. A method for ventilating a patient with aventilator comprising: during a spontaneous mode of ventilation,monitoring at least one fatigue indicator; based on monitoring the atleast one fatigue indicator for a period of time, establishing abaseline for the at least one fatigue indicator; determining a changefrom the baseline of the at least one fatigue indicator; comparing thechange to a corresponding fatigue threshold; based on the comparison,detecting respiratory fatigue; and in response to detecting respiratoryfatigue, displaying a fatigue notification and switching from thespontaneous mode of ventilation to a mandatory mode of ventilation. 2.The method of claim 1, wherein the step of detecting respiratory fatiguecomprises: determining that the change breaches the correspondingfatigue threshold.
 3. The method of claim 1, wherein the fatiguenotification includes at least one of the following notifications:fatigue detection; a level of fatigue; a fatigue index; thecorresponding fatigue threshold; fatigue detected; fatigue implicated; afatigue warning; or a notice of fatigue.
 4. The method of claim 1, priorto monitoring the at least one fatigue indicator during the spontaneousmode of ventilation, the method further comprising: ventilating thepatient based on the mandatory mode of ventilation; and switching fromthe mandatory mode of ventilation to ventilate the patient based on thespontaneous mode of ventilation.
 5. The method of claim 1, wherein thefatigue notification includes a recommendation message.
 6. The method ofclaim 5, wherein the recommendation message is selected from a group ofthe following recommendation messages: consider switching to invasiveventilation; consider switching to a negative feedback breath type;consider switching to a pressure support (PS), pressure control (PC),volume control (VC), or volume support (VS) breath type; considerincreasing a support setting in a proportional assist (PA), breath type;consider increasing a support setting in a diaphragmaticelectromyography adjusted (DEA) breath type; consider increasing asupport setting in a positive feedback breath type; consider increasinga set respiratory rate; consider utilizing a basal level of support inthe PA breath type; consider utilizing a basal level of support in theDEA breath type; and consider utilizing a basal level of support in thepositive feedback breath type.
 7. The method of claim 1, furthercomprising: delivering ventilation based on a positive feedback breathtype; and implementing a basal level of support for the positivefeedback breath type in response to detecting respiratory fatigue. 8.The method of claim 7, wherein the basal level of support is at least 5cmH₂O.
 9. The method of claim 7, further comprising: monitoring thefatigue indicator after a rest time, wherein the rest time begins inresponse to implementing the basal level of support; comparing therested fatigue indicator to the baseline; in response to the comparison,determining that the respiratory fatigue was mitigated by implementingthe basal level of support.
 10. The method of claim 1, furthercomprising: delivering ventilation based on a breath type selected froma group of a proportional assist (PA) breath type and a diaphragmaticelectromyography adjusted (DEA) breath type; and delivering ventilationbased on a non-positive feedback breath type after the step of detectingrespiratory fatigue.
 11. The method of claim 1, wherein establishing thebaseline includes receiving the baseline from clinician input.
 12. Themethod of claim 1, wherein the at least one fatigue indicator and thecorresponding fatigue threshold are selected from a group consisting of:a work of breathing decrease below the baseline, a work of breathingincrease above the baseline followed by a work of breathing decreasebelow the baseline, a partial pressure of carbon dioxide in the blood(PaCO₂) increase of at least 10 mmHg from the baseline, a volume ofcarbon dioxide (VCO₂) decrease of more than 20% from the baseline, anelectromyography (EMG) of an accessory muscle indicates use of theaccessory muscle, an electrical activity of the diaphragm (E_(di))decrease of at least 25% from the baseline, an E_(di) that stays thesame while a velocity of muscle shortening decreases below the baseline,a diaphragmatic position (P_(di)) decrease of at least 10% from thebaseline, a maximal transdiaphragmatic pressure (P_(di,max)) decrease ofat least 20% from the baseline, a maximal inspiration pressure(P_(i,max)) decrease at least 20% from the baseline, the velocity ofmuscle shortening decreases at least 25% from the baseline, an EMG timedomain is less than 50 uV, an EMG frequency domain decrease of more than20% from the baseline, an esophageal pressure (P_(esoph)) decrease of atleast 10% from the baseline, a P_(di) Maximum Relaxation Rate decreaseof at least 20% from the baseline, an estimated inspiratory musclepressure (P_(mus)) Maximum Relaxation Rate decrease of at least 20% fromthe baseline, a presence of paradoxical breathing, an exhaled alveolarvolume (V_(e alv)) decrease of at least 20% from the baseline, arespiration rate increase above 35 breaths a minute, a respiration rateincrease of at least 25% from the baseline followed by a decrease, atidal volume divided by inspiration time (V_(t)/T_(i)) decrease of 30%from the baseline, a dead space ventilation volume divided by tidalvolume (V_(d)/V_(t)) increase of 20% from the baseline, the V_(d)/V_(t)is greater than 40% from the baseline, an occlusion pressure of theairway at 100 ms (P_(0.1)) increases above 4 cm of H₂O and thendecreases by at least 2 cm of H₂O, a diaphragmatic position becomesflattened, a cardiac output does not increase with an increasing load, atidal volume (V_(t)) is below 4 mL/kg, a diaphragm movement imagingshows reduced movement compared to the baseline, alternatingabdominal/rib cage muscle contractions occur or increase in frequencycompared to the baseline, a bispectral index level of sedation (BIS LOS)is normal, a Rapid Shallow Breathing Index (RSBI) increases above 105, aP_(di)/P_(di max) is above 40%, an inspiration time divided by totaltime of the breath cycle (T_(i)/T_(tot)) is greater than 40%, a pressuretime index (P_(tid)) increases above 0.15,T_(i)/T_(tot)/P_(di)/P_(dimax) is greater than 40%, E_(di) increaseswhile electrical activity of the phrenic nerve (E_(phr)) increases andP_(di) decreases, the P_(di,max) increases from the baseline, theP_(i,max) increases from the baseline, E_(di) increases from thebaseline and at least one of a decrease in V_(t), a decrease in VCO₂, adecrease in oxygen saturation level of the blood (SpO₂), an increase inP_(0.1), or a decrease in minute volume (MV) occurs, and P_(mus)decreases from the baseline and at least one of a decrease in V_(t), adecrease in VCO₂, a decrease in SpO₂, or a decrease in MV occurs. 13.The method of claim 1, wherein establishing the baseline includesaveraging a set of measurements for a plurality of fatigued indicatorsfor an amount of time.
 14. A ventilator system comprising: a pressuregenerating system adapted to generate a flow of breathing gas; aventilation tubing system including a patient interface for connectingthe pressure generating system to a patient; a plurality of sensorsoperatively coupled to at least one of the pressure generating system,the patient, or the ventilation tubing system, wherein the plurality ofsensors monitor a plurality of parameters to generate sensor output; anda memory storing computer-executable instructions that, when executed bya processor, cause the ventilator system to: based on monitoring atleast one fatigue indicator during a spontaneous mode of ventilation fora period of time, determine a baseline for the at least one fatigueindicator; determine a change in the at least one fatigue indicator fromthe baseline based on the sensor output; compare the change to acorresponding fatigue threshold to determine that the patient isfatigued; in response to detecting respiratory fatigue, display anotification; and switch from the spontaneous mode of ventilation to amandatory mode of ventilation.
 15. The ventilator system of claim 14,wherein the computer-executable instructions further cause theventilator system to determine that the change breached thecorresponding fatigue threshold.
 16. The ventilator system of claim 14,the computer-executable instructions further causing the system to:derive the at least one fatigue indicator from the sensor output. 17.The ventilator system of claim 14, wherein the notification includes arecommendation message selected from a group of the followingrecommendations: consider switching to invasive ventilation; considerswitching to a negative feedback breath type; consider switching to apressure support (PS), pressure control (PC), volume control (VC), orvolume support (VS).breath type; consider increasing support setting ina proportional assist (PA) breath type; consider increasing supportsetting in a diaphragmatic electromyography adjusted (DEA) breath type;consider increasing support setting in a positive feedback breath type;consider increasing set respiratory rate; consider utilizing a basallevel of support in the PA breath type; consider utilizing a basal levelof support in the DEA breath type; and consider utilizing a basal levelof support in the positive feedback breath type.
 18. The ventilatorsystem of claim 14, wherein after determining that the patient isfatigued, the computer-executable instructions further cause theventilator system to: instruct the pressure generating system to delivera baseline level of support for a rest time; after the rest time,determine a rested fatigue indicator based on the sensor output; comparethe rested fatigue indicator to the baseline; and based on thecomparison, determine that the patient was fatigued.
 19. The ventilatorsystem of claim 14, wherein the at least one fatigue indicator isselected from a plurality of fatigue indicators and correspondingfatigue thresholds comprising one or more of: a work of breathingdecrease below the baseline, a work of breathing increase above thebaseline followed by a work of breathing decrease below the baseline, apartial pressure of carbon dioxide in the blood (PaCO₂) increase of atleast 10 mmHg from the baseline, a volume of carbon dioxide (VCO₂)decrease of more than 20% from the baseline, an electromyography (EMG)of an accessory muscle indicates use of the accessory muscle, anelectrical activity of the diaphragm (E_(di)) decrease of at least 25%from the baseline, an E_(di) that stays the same while velocity ofmuscle shortening decreases below the baseline, a diaphragmatic position(P_(di)) decrease of by at least 10% from the baseline, a maximaltransdiaphragmatic pressure (P_(di,max)) decrease of at least 20% fromthe baseline, a maximal inspiration pressure (P_(i,max)) decrease of atleast 20% from the baseline, the velocity of muscle shortening decreasesat least 25% from the baseline, an EMG time domain is less than 50 uV,an EMG frequency domain decrease of more than 20% from the baseline, anesophageal pressure (P_(esoph)) decrease of at least 10% from thebaseline, a P_(di) Maximum Relaxation Rate decrease of at least 20% fromthe baseline, an estimated inspiratory muscle pressure (P_(mus)) MaximumRelaxation Rate decrease of at least 20% from the baseline, a presenceof paradoxical breathing, an exhaled alveolar volume (V_(e alv))decrease of at least 20% from the baseline, a respiration rate increaseabove 35 breaths a minute, a respiration rate increase of at least 25%from the baseline followed by a decrease, a tidal volume divided byinspiration time (V_(t)/T_(i)) decrease of 30% from the baseline, a deadspace ventilation volume divided by tidal volume (V_(d)/V_(t)) increaseof 20% from the baseline, the V_(d)/V_(t) is greater than 40% from thebaseline, an occlusion pressure of the airway at 100 ms (P_(0.1))increases above 4 cm of H₂O and then decreases by at least 2 cm of H₂O,a diaphragmatic position becomes flattened, a cardiac output does notincrease with an increasing load, a tidal volume (V_(t))is below 4mL/kg, a diaphragm movement imaging shows reduced movement compared tothe baseline, alternating abdominal/rib cage muscle contractions occuror increase in frequency compared to the baseline, a bispectral indexlevel of sedation (BIS LOS) is normal, a Rapid Shallow Breathing Index(RSBI) increases above 105, a P_(di)/P_(di max) is above 40%, aninspiration time divided by total time of the breath cycle(T_(i)/T_(tot)) is greater than 40%, a pressure time index (P_(tid))increases above 0.15, T_(i)/T_(tot)/P_(di)/P_(dimax) is greater than40%, E_(di) increases while electrical activity of the phrenic nerve(E_(phr)) increases and P_(di) decreases, the P_(di,max) increases fromthe baseline, the P_(i,max) increases from the baseline, E_(di)increases from the baseline and at least one of a decrease in V_(t), adecrease in VCO₂, a decrease in oxygen saturation level of the blood(SpO₂), an increase in P_(0.1), or a decrease in minute volume (MV)occurs, or P_(mus) decreases from the baseline and at least one of adecrease in V_(t), a decrease in VCO₂, a decrease in SpO₂, or a decreasein MV occurs.
 20. A computer-readable medium having computer-executableinstructions for performing a method of ventilating a patient with aventilator, the method comprising: during a spontaneous mode ofventilation, repeatedly monitoring a plurality of fatigue indicators;establishing a corresponding baseline for each of the plurality offatigue indicators; repeatedly evaluating whether each of the monitoredplurality of fatigue indicators has changed from the correspondingbaseline; in response to determining a change for a fatigue indicator,comparing the change to a corresponding fatigue threshold; in responseto the comparison, detecting respiratory fatigue; and in response todetecting respiratory fatigue, displaying a fatigue notification andswitching from the spontaneous mode of ventilation to a mandatory modeof ventilation.